Since there is a whole range of technical issues and limitations in the application of the 'Bottom up' printing principle, these problems are solved by the application of this invention.

This invention includes the system for constant liquid level maintenance in the container, the use of the roller passing over the very surface of the photopolymer material at which the polymerization of 3D model is performed, the use of a higher specific gravity liquid mixed with the photopolymer in a container in which 3D model printing and dynamic mixing of the photopolymer is taking place. Summarized, the complete process consists of three individual implementations and one method for photopolymer preparation, which form a whole:

1. Movable secondary containers for constant liquid level maintenance in the container in which the 3D model is printing,

2. Roller passing over the photopolymer surface,

3. Saturated liquid in the container in which printing of the 3D model is performed

4. Photopolymer mixing and cooling

The application of this complete procedure enables higher speeds of 3D models printing, achieves higher precision of printed 3D models and ultimately reduces the costs of making 3D models printed using DLP 3D technology. In addition, the application of this invention enables high-quality and precise printing of 3D models of unlimited dimensions.

According to the International Patent Classification (IPC), this invention is classified as:

- B01D - Separation in general

- B01D 17/02 - Separation of non-mixing liquids

- B01D / C02F - Water treatment

- B05 - Dispersion or spraying in general; application of liquids or other liquid materials on surfaces, in general

- B29 - Processing of plastic materials, processing of substances in plastic state

- B29C 37/00 - Components, details, accessories or auxiliary operations

- B67C 3/28 - Devices for volume control when filling bottles with liquids

- B67D - Pouring, dispensing or transferring liquids - F28 - Heat exchange, in general - G03 - Devices or processes for photosensitive material preparation or processing

- G05 - Management; control

- G05D 9/00 - Level management, e.g. managing the amount of material stored in the container - G05D 9/02 - without auxiliary source of energy

Technical issue

In the current application of DLP tecnology, the 'Bottom up' printing principle (Figure 2) is mostly used, where the photopolymer 4 is illuminated from below 3, i.e. through the container 1. Using this technology, to enable the light to illuminate the photopolymer, container's bottom is made of transparent foil 5 (so-called FEP foil). This foil provides an ideally flat layer of the photopolymer 4 on the illuminating surface 22. Flowever, during the process the foil 5 stretches and thus wears out. Due to this stretching of foil 5, this technology can only work with photopolymers 4 of the highest quality and therefore the most expensive ones.

Because of this feature of stretching the foil, it is also impossible to make a 3D printer of large working dimension.

The 'Bottom up' (Figure 2) principle is very successful and is used in 3D printing jobs for extremely small and precise models. However, for larger models (larger than 10 cm) this technology is not suitable.

DLP printing technology applied in this way also brings several issues that affect the quality and speed of printing.

One of issues is the deposition of pigment 6 at the bottom of the container 1 in which the photopolymer 4 for printing is located. Namely, photopolymers are transparent liquids to which pigment is added if you want to get a special colour of photopolymer, and the 3D model 2 is printed in this colour. During the rest and printing, pigment 6 is deposited at the bottom of the container 1 and this requires occasional printing interruptions, container cleaning, mixing and re-adding of the photopolymer 4.

85 All of this has an impact on the speed and repeatability of printing and, at the same time, affects the price increase of the printed model and the entire printing process.

The second issue is heating of the photopolymer 4 during printing. Namely, photopolymerization is an exothermic process in which heat is released and 90 heats up the photopolymer 4. Such heated photopolymer is not suitable for re-illumination with UV light. As its temperature increases, the polymerization reaction slows down, resulting in incomplete hardening of the layers printed in such conditions. Ideally, the photopolymer 4 is at room temperature. In order to achieve this by using existing technology, it is 95 necessary to extend the period between two illuminations with UV light 3, which then prolongs the printing time of the 3D model 2 and, finally, affects the cost of the printed 3D model 2.

The third issue is maintaining a constant distance between the UV light projector 3 and the polymerization surface 22. Namely, during the printing of loo 3D model 3, part of the photopolymer mass 4 ends up in the 3D model 2. In 'Top down' technology (Figure 3), after the 3D model 2 printout is done, it is pulled upwards along the 'Z' axis and thus the quantity of remaining photopolymer 4 in the print container is reduced (Figure 4A & Figure 4B). When manually adding the photopolymer mass 4 by the user, it is almost 105 certain that there will be a change in the distance between the projector 3 and the surface of the photopolymer 22 because manual pouring cannot be precise enough. This issue directly affects print repeatability and print speed itself.

All issues specified above have an impact on the speed, quality and no repeatability of the printout and the impossibility to print 3D models 2 of larger dimensions, which in turn affects the high cost of printing.

Description of related art

DLP technology of 3D model 2 printing has been known for many years. The basic principle is illumination of photopolymer 4 with UV light 3, than this 115 part of the photopolymer 4 hardens on the polymerization surface 22. A complete 3D model 2, attached to the platform 7, is created by repeating the process of layer-by-layer illumination.

With DLP 3D printing technology, two operating principles are applied. They are 'Bottom up' (Figure 2) and 'Top down' (Figure 3) operating principles. The 120 basic difference is how the photopolymer 4 in the container 1 is illuminated. When using 'Top down' (Figure 3) operating principle, the surface of the photopolymer 22, located in the container 1 in which the polymerization and 3D printing is performed, is illuminated. When using 'Bottom up' (Figure 2) operating principle, the bottom of the container 1 is illuminated, in which 125 the photopolymer 4 is located and in which the polymerization on lower surface 22 and 3D printing is performed.

In addition, these two principles are distinguished by the fact that when using 'Top down' printing principle, during 3D model 2 printing, until completed, it is immersed in the container 1 with photopolymer 4, and when 130 using 'Bottom up' printing principle, during 3D model 2 printing, until completed, it emerges from the container 1 in which the photopolymer 4 is located. Nowdays, it is mostly used 'Bottom up' operating principle, where UV light 3 illuminates the bottom of the container 1 containing photopolymer 4 which then hardens. The 3D Model 2 layer thus created rises along the 'Z' axis for the selected size. Subsequent illumination of the photopolymer 4 creates a new layer of the 3D model 2 that rises again along the 'Z' axis and, depending on the size of the printed 3D model 2, slowly rises above the surface of photopolymer 4. Repeating this procedure ultimately creates the desired 3D model 2.

Upon completition of printing, the entire 3D model 2 rises above the surface of the photopolymer 4 and can be removed from the platform 7 to which the 3D model 2 is attached.

This printing principle is very successful and is used to create extremely small and precise models.

Disadvantages of this operating principle are:

- it is not suitable for making larger models (larger than 10 cm),

- process uses foil 5 which has to be cleaned and changed frequently,

- for these reasons, only photopolymers 4 belonging to the highest price class, can be used.

The invention described here just solves all the above mentioned disadvantages and improves the process of 3D printing using DLP technology in terms of quality, speed, lower printing costs and opens the possibility to print models of unlimited dimensions.

Exposing the essence of the invention

The primary objective of this invention is to improve DLP 3D print technology in terms of increasing the speed and accuracy of printed 3D models. The secondary objective of this invention is to enable printing of unlimited dimensions of 3D models by using DLP technology while meeting the highest 160 criteria of precision and quality.

A further objective of the invention is to reduce the costs of 3D models printing using DLP technology.

Additional objectives and advantages of the invention will be exposed in the description which follows, and partly will become apparent from the 165 invention application.

Process of photopolymer material preparation with application in DLP 3D printer, according to this invention, includes two devices and one method for photopolymer preparation, which together form an innovative technological whole, whose application in 3D DLP printers achieves the following basic 170 objectives set for this invention: higher speed of 3D model printing, higher precision of printed 3D models and the possibility to print models of unlimited dimensions, which ultimately leads to a lower costs of 3D models printing.

The two devices covered by this invention are: an overflow system for 175 maintaining a constant liquid level (Figure 4A & Figure 4B) and a translational-rotary roller which passes over the surface of the photopolymer on which the polymerization is performed (Figure 5).

The process (method) for preparing the photopolymer which is also included in this invention and forms a whole with above mentioned two devices, is iso the placement of the photopolymer in a common container with the saturated liquid (Figure 5 & Figure 10) and its occasional mixing (Figure 11, Figure 12A and Figure 12B ).

By implementing the above two devices and the method for preparing photopolymer 4, the following technical issues that are now present in printing using DPL technology are solved: deposition of pigments 6 and 20 from photopolymers 4 and 18, heating the surface i.e. layer of photopolymer on which the polymerization 22 is performing, maintaining a constant distance between the projector 3, as a source of UV light, and the photopolymer surface 22 on which the hardening process is taking place and, at the same time, the prerequisites for printing of unlimited dimensions of 3D models 2 are met.

This invention is the most effective when applied in DLP printers using 'Top down' operating principle (Figure 3).

For better understanding, the process of placing the photopolymer 4 and the saturated liquid 19 in the common container 1, where the printing is performed, is described separately:

Using the procedure and the method for preparing the photopolymer 4, by which the photopolymer 18 is placed in the common container with saturated liquid 19 (Figure 10) and where, by the procedure, is occasionally mixed (Figure 11, Figure 12A and Figure 12B), it is resolving the technical issue of pigment deposition 6 at the bottom of the container 1 in which the photopolymer 4 is located and in which the printing is performed. In order to avoid deposition, this invention implements a solution by mixing the photopolymer 18 with water in the same container in which the printing is performed (Figure 10). The photopolymer is not soluble in water, and since the densities of water and photopolymer are relatively similar, the effect of pouring photopolymer into the water results in floating of photopolymer accumulations in water. According to this invention, the salt is added to the water until saturated (or any other water-soluble substance) before mixing with the photopolymer. In this way, an increase in the density of water 19 is achieved, which causes the photopolymer resin, which is now of lower density, to rise above the water on its surface (Figure 10, sign 18). After this segmentation, there is a layer of photopolymer resin 18 in the container, which lies on the surface of the newly formed mixture (FigurelO), and saturated water 19 is in the remaining part of the container. This creates an interface between the photopolymer resin and the saturated water.

The effect of application of this invention when using the 'Top down' (Figure. 11) operating principle is that, at the rest mode or during the printing phase, the pigment from the photopolymer 18 will be deposited in the layer 20 between photopolymer 18 and saturated liquid 19 and will not deposit at the bottom of the container (Figure 2 & Figure 3, pos. 6), which is otherwise an issue in the printing process that results in downtime, cleaning of the deposited pigment 6 and replacement of the foil 5. Thus, the application of this invention enables continuous printing of 3D model 2 without unnecessary delays, with the continuous possibility of repeatability of printing 3D models 2.

In this way, it is also facilitated the mixing of the deposited pigment 20 with the photopolymer that is in the layer 18, because by appropriate number of passes of the platform 7 on which the 3D model is printed, through the interface of photopolymer 18 and pigment 20, they are completely mixed (Figure 11, Figure 12A and Figure 12B). Referring to Figure 12A, the start time of the process 21 of mixing the deposited pigment 20 and the photopolymer 18 is shown. The platform 7, which is driven by an external force, moves along the 'Z' axis, emerging upwards above the surface of the photopolymer 18, then immersing again in depth to saturated fluid 19, passing through the photopolymer 18 and the deposited pigment 20, and then the platform 7 performs a backward movement upwards, passing again through the deposited pigment 20 and the photopolymer 18. This movement of the platform 7 is repeated until the photopolymer 18 and the deposited pigment 20 are completely mixed. Referring to Figure. 12B, the moment when the photopolymer 18 is prepared for further printing is shown. Mixing can also be done during printing, which is extremely important when printing large 3D models, and for that reason allowing unlimited duration of printing, without interrupting the printing process. The first device which is part of this invention is the translation-rotation roller (Figure 5) which passes over the photopolymer 4 surface on which the polymerization 22 is performed. The roller 8 is driven by external force. The purpose of the roller 8 is to quickly apply the material on the surface, to flatten the surface and to dynamically cool the surface of the photopolymer material 4 on which the polymerization 22 is performed. After each illumination of the photopolymer surface 22, the roller 8 makes a movement 14 from one side to the other side of the container. This movement is made at the very surface of the photopolymer 4. After illuminating the surface 22, the roller makes a movement 14 from left to right (Figure 7) to the edge where it stops and then the new illumination is performed. When it is finished, the roller 8 makes a movement 14 from right to left (Figure 6) to the edge where it stops, after which the surface is illuminated again. After each illumination, the platform 7 makes a movement along the 'Z' axis for the required polymerization thickness of a new layer of the future 3D model 2. This 'illumination - roller motion - illumination - roller motion' dynamics is performed for the entire printing time of 3D Model 2 until the final completion of printing.

While the translation of the roller 8 is performed to one side, the rotation of the roller 15 is always opposite to the translation movement 14. When the roller 8 moves from left to right (Figure 7), the rotation of the roller 15 is counterclockwise. Vice versa, when the roller 8 moves from right to left (Figure 6) the rotation of the roller 15 is clockwise. The translational- rotational movement of the roller 8 realized in this way causes the photopolymer 22 surface to be leveled and the heated photopolymer 4 to be removed from the photopolymer surface 22 after polymerization. An additional effect of the movement and rotation of the roller is also mixing the photopolymer with the deposited pigment (Figure 9).

In order to achieve the full functionality of the roller, the roller 8 has a limiter 9 placed on its upper side, which prevents the photopolymer material 4 to return to the part that the roller 8 has already passed in its movement. Also, at the end of the container 1 a partition 10 is placed, to which the roller 8 moves in its horizontal movement. The function of the partition is to prevent laminar backflow of the photopolymer (Figure 9). After the roller 8 reaches the partition 10, the accumulated photopolymer 4, picked up by the roller 8 in its motion (Figure 8, call sign 17), will be transferred over the partition 10 and mixed with the other colder photopolymer. The movement of thus transferred photopolymer 17 is shown by arrows 16 on Figure 16.

It should be emphasized here that the saturated liquid 19, which is in direct contact with the photopolymer 4, also plays a major role in the cooling of the photopolymer 4. This allows the saturated liquid 19 to constantly remove excess heat from the photopolymer 4 and due to an arbitrarily large difference in the volume of the saturated liquid 19 and the photopolymer 4, located in the container 1, the system can always be calibrated to be constantly in a state of thermal equilibrium. Another device which is part of this invention is the 'Device for maintaining a constant set liquid level in the container' (Figure 4A and Figure 4B), which is, as a patent application, registered with the State Intellectual Property Office of the Republic of Croatia and assigned an application number P2019038A. The device for maintaining a constant liquid level in the container, according to this invention, comprises two containers 1 and 11, inter-connecting hose 13 and a spring 12 on which one of the containers 11 is suspended, creating a unique whole of two containers, connecting hose and a spring. The container 1, in which the fluid level is maintained, is fixed, and container 11 hanging on the spring 12 is movable in vertical direction, allowing movement upwards and downwards. The fixed container 1, according to this invention, is a container in which there is a mixture of photopolymer 4 and saturated liquid 19 (Figure 5) and where it is necessary to maintain a constant level of photopolymer 4. The movable container 11 is an auxiliary container in the device, which is used exclusively as a tank for saturated liquid 19 which is used to amortize changes in the level of the photopolymer 4 in the fixed container 1.

All details of the work, along with patent claims, are described in said patent application under number P2019038A.

By implementing the invention described so far with the above solutions, and in relation to the existing DLP 3D printing system, the following advantages are achieved:

- The application of the device described above solves the issue of maintaining the same level of the photopolymer 4 in the container 1 and thus maintaining the same distance between the projector 3 (UV light source) and the surface of the photopolymer on which the printing 22 is performed.

- The issue of heat accumulation on the photopolymer surface 22 has been solved. This heat accumulation causes polymerization reaction to slow down and leads to a violation of the integrity of the printed object 2 and the entire process.

- The issue of limited dimension of printed 3D model 2 has also been solved. By implementing this invention, the printed 3D model 2 can be of unlimited dimensions both horizontally and vertically.

- The issue of pigment deposition 6 has been solved, which otherwise could result in downtime.

- Finally, the complete implementation of the described invention significantly reduces the cost of 3D printing with DLP technology.

Brief description of drawings

The accompanying drawings, which are included into description and constitute a part of the invention description, illustrate the best method for invention performance discussed so far and help to explain the basic concepts and methods for invention functioning.

- FIG. 1 - spatial appearance of the preparation process application for the photopolymer material and devices with application in DLP 3D printer that result in faster and more accurate printing of 3D models,

- FIG. 2 - drawing of the 'Bottom up' operating principle of DLP printer showing FEP foil and pigment deposition at the bottom of the container,

- FIG. 3 - drawing of the 'Top down' operating principle of DLP printer showing the pigment deposition at the bottom 1 of the container,

- FIG. 4A - drawing of the overflow system for maintaining a constant level of liquid in the container in which 3D model is printed,

- FIG. 4B - view of reduction of photopolymer quantity in the container in which the 3D model is printed, - FIG. 5 - drawing of the translation-rotation roller with a view of the photopolymer on the surface of the saturated liquid and a view of the partitions at the edge of the container in which the printing is performed and the drawing of the device for maintaining a constant liquid level,

- FIG. 6 - drawing of the movement of the translation-rotation roller to the left, showing the roller rotation,

- FIG. 7 - drawing of the movement of the translation-rotation roller to the right showing the roller rotation,

- FIG. 8 - drawing and view of the accumulated photopolymer on the roller when moving to the right,

- FIG. 9 - drawing and view of the flow of accumulated photopolymer that the roller pushes in front of it at the moment when the roller reaches the end point - the partition,

- FIG. 10 - drawing and view of photopolymers in the common container with saturated liquid,

- FIG. 11 - drawing and view of deposited pigment at the photopolymer and saturated liquid interface,

- FIG. 12A - drawing and view of deposited pigment and saturated liquid mixing,

- FIG. 12B - drawing and view of mixed pigment with photopolymer where the printer is ready for further 3D model printing.

Detailed description of at least one method for invention realization Reference will now be made in detail to this assumed embodiment of the invention, one example of which is illustrated by the drawings. Referring to Figures 1, 4A, 4B and 5, it is visible that the whole process of photopolymer material preparation and the device system with application in the DLP 3D printer consists of the fixed container (1) containing the photopolymer (4), and the movable container (11) suspended on the spring (12), the connecting hose (13) and the translational-rotating roller (8).

These drawings show that the process consists of two devices, namely the overflow system referred to by Figures 4A and 4B and the translation- rotation roller (8) referred to by Figure 5, which consists of the movable container (11) suspended on a spring (12), the connecting hose (13) from the fixed container (1).

Referring to FigurelO, it is visible that the part of the process, according to this invention, is to place the photopolymer (18) and the saturated liquid (19) in the common container (1) in which the printing is performed. It is also visible here that, due to the difference in the density of the photopolymer (18) and the saturated liquid (19), these two media are separated and that the photopolymer (18) is then located on the surface of the saturated liquid (19) forming an interface between the photopolymer and saturated liquid. Figurell indicates that then the deposition of pigment (20) forms at the lower part of the photopolymer (18) and, at the same time, on the surface of the saturated liquid (19), so the pigment (20) is no longer deposited at the bottom of the container (1) in which the 3D model (2) is printed.

Referring to Figure 2, the 'Bottom up' operating principle is shown, which is currently the most common in DLP printers. The drawing also shows the pigment deposition (6) at the bottom of the container (1), which is a major issue with this technology. In this operation principle, the pigment (6) is deposited on a special foil (5) which is located at the bottom of the container (1) and which is used in this operating principle of a 3D printer. Referring to Figure 3, the 'Top down' operating principle of a DLP printer is shown, showing the pigment deposition (6) at the bottom of the container. Referring to Figures 11, 12A and 12B, it is visible that the entire process is rounded by the mixing process of the photopolymer (18) located on the saturated liquid surface (19) in which the printing platform (7) performs intermittent motion, immersing and emerging from saturated liquid (19), passing through the deposited pigment (20) and photopolymer (18), and thus mixes the deposited pigment (20) with the photopolymer (18) present on the surface. After appropriate number of passes of the platform (7), the photopolymer (18) is mixed with the pigment and ready again for further high-quality printing of the 3D model, which is visible in Figure 12B.

Referring to Figures 4A and 4B, an overflow system for maintaining a constant liquid level in the container in which the 3D model is printed (2) is shown. The purpose of this device is to maintain a constant distance between the photopolymer surface (22), on which the polymerization performs, and the UV light source (3) which is visible in Figure 3. The disturbance of the required distance occurs when the finished 3D model (2), together with the platform (7), emerges from the photopolymer (4) so it could be removed from the platform (7), which is visible in Figure 4B. At this point, the 'Device for maintaining constant liquid level in container' takes over the function of correcting the liquid level in the container (1) in which the 3D model (2) is printed. The basis of this device operation consists in the fact that the movable container (11) is suspended on a spring (12) and is connected with the connecting hose (13) to the container (1) in which the printing is performed. Any change in the level of the photopolymer (4) in the container (1) will result in liquid inflow from the auxiliary container (11) into the container in which the printing (1) is performed. In this way, the required 17 level of photopolymer in the container (1) is maintained and thus the appropriate distance between the polymerization surface (22) and the UV light source (3) will be achived. Details of the operation of the 'Device for maintaining a constant liquid level in container' are described in patent application to the State Intellectual Property Office (Croatia) under the number P2019038A, the inventors of which are the same as the inventors of this patent application.

Figure 5 refers to the drawing of the translation-rotation roller (8) passing over the surface of the photopolymer (4), preparing a layer of photopolymer on which the polymerization is performed (22). The roller (8) is driven by an external force, and its purpose is to quickly apply and level the surface of the photopolymer material (4) and to cool the photopolymer surface on which the polymerization (22) performs.

Referring to Figure 6, 7 and 8, it is visible that the roller (8) moves from left to right (14) and back from right to left (14). In the container (1) in which the platform (7), on which the printing is performed, is located, partitions (10) are placed on each side of the container (1). The movement of the roller (8) is performed from the partition (10) on the left side of the container (1) to the partition (10) which is placed on the right side of the container (1) and back. This movement dynamics of the roller (8), from one side of the container (1) to the other side of the container (1), is performed for the entire 3D model printing time until the completion of printing. This procedure is designed so when the roller (8) reaches the partition (10) in its motion, it stops there, and during its rest time the surface of the photopolymer (22) is illuminated with UV light. After polymerization and hardening of one layer of the printed 3D model (2), the platform (7) is lowered into the photopolymer (4) for the selected value of the thickness of the printing layer after which the roller (8) again passes to the other side of the container (1) where it stops again. After that, the surface of the photopolymer (22) is illuminated with UV light, creating a new layer of the printed 3D model. After the illumination is done, the platform (7) is lowered into the photopolymer (4), the roller (8) begins its movement and the whole process is repeated.

This 'roller movement - lighting - platform lowering - roller moving - lighting - platform lowering' dynamics and so on is performed for the entire printing time of 3D Model 2 until the printing is completed.

Figures 6 and 7 also indicate that the roller rotation (15) is always opposite to the roller (8) translational movement (14). When the roller (8) moves from left to right (Figure 7), the roller rotation (15) is counterclockwise and when the roller (8) moves from right to left (Figure 6) the roller rotation (15) is clockwise. The translational-rotational movement of the roller (8) realized in this way causes the photopolymer surface (22) to be leveled and heated photopolymer (4) formed on the photopolymer surface (22) during polymerization to be removed. An additional effect of the roller movement and rotation is also mixing the photopolymer with the deposited pigment (Figure 9).

Referring to Figure 8, it is visible that the roller (8) in its movement and rotation pushes a part of photopolymer material (17) in front of it from the surface of the photopolymer (4). It is this procedure that levels and prepares the photopolymer (4) and removes the heat from the photopolymer (4) surface. It is visible in Figure 9, when the roller (8) reaches the partition (10) with the direction of movement shown by call sign 16, the accumulated (pushed) photopolymer (4) is transferred over the partition (10) to immerse into the saturated liquid (19). At this moment, part of the heat is transferred from the photopolymer (4) to the saturated liquid (19). The entire process is completed here in such a way that at that moment the mixing of the photopolymer (4) and the deposited pigment (20) is performed, which pigment has formed as a layer at the interface between the photopolymer in the container with saturated liquid (18) and the saturated liquid (19), and which is separately shown as a specific characteristic in Figures 10 and 11.

In order to fully achieve the roller (8) functionality, Figures 5, 6, 7 and 8 indicate that the roller (8) has a limiter (9) on its upper side which prevents the photopolymer material (4) to be brought back to the part already passed over by the roller (8) in its motion. In this way, it is ensured that the hottest photopolymer (4) is removed from the polymerization surface (22) and the surface, already passed over by the roller (8), remains prepared for new illumination.

Method of application of the invention

Thus, the invention provides a practical and useful process and device that can be economically implemented and manufactured and which includes significant improvements over previously known methods and devices of this type.

During realization, this invention could experience a number of modifications and changes, without abandoning the scope and spirit of the invention. List of call signs

In order to better understand drawings and process description, here is the list of call signs used in drawings:

1. Container with a photopolymer

2. Printed 3D model 3. UV light source

4. Photopolymer

5. FEP foil

6. Deposited pigment

7. Platform on which printing is performed 8. Translational-rotary roller

9. Excess material limiter

10. Partition (septum)

11. Movable container for maintaining a constant level of photopolymer 12. Spring on which the movable container is suspended 13. Connecting hose

14. Direction of roller movement

15. Direction of roller rotation

16. Movement of the photopolymer transferred over the partition

17. Accumulation of photopolymer pushed by the roller from the surface of the photopolymer

18. A layer of photopolymer in the container with saturated liquid 19. Saturated liquid

20.A layer of deposited pigment between photopolymer and saturated liquid 21. Photopolymer mixing process

22. Polymerization surface