Printing on a flat surface and printing on a curved one are fundamentally different problems, because a flat-bed UV printer applies ink to a static surface, while a cylindrical object needs to move at a precise, continuous rate under the print head for the image to wrap evenly instead of stretching or distorting. The Rotary Printing Attachment solves this by replacing the E1's flat print bed with a rotating cradle, turning the object itself into a moving surface that's synchronised with the print head's pass, and this is what allows artwork to wrap around a tumbler or bottle without warping at the seams.

Before that rotation starts, auto-levelling measures the object's shape and diameter and adjusts the print head's distance accordingly, which matters because UV (ultraviolet) ink needs a consistent gap from the nozzle to cure and adhere properly, since too far and detail softens, while too close and the head risks contact. This is also why the attachment works across a defined diameter range of 4.1–10 cm and tapered angles under 15°, since beyond those tolerances, the auto-levelling system can no longer maintain a consistent print distance across the full rotation, so accuracy would drop.

The same underlying UV-curing process that gives the E1 its raised, textured print capability on flat items carries over here, letting the attachment build embossed detail up to 1 mm high on a curved surface, and this is only possible because the ink cures layer by layer in sync with the object's rotation, rather than being printed and dried in one pass. In practice, this means the mechanism that makes flat 3D-texture printing possible on the E1 is the same one that makes accurate, textured cylindrical printing possible here, so the attachment isn't a separate print engine but rather an extension of the E1's existing process onto a rotating axis.