Minecraft wiki entry for Printing, associated text: Most 2D printer designs have three basic parts: the input (a chest), the "stock" (several piles of concrete powder), and the pistons to create the output. A sorting system removes the items from the chest. The concrete powder that is ready to be printed is on top of extended pistons. The pistons that correspond to the colors requested retract for a long enough time to allow one concrete powder from the stack to fall onto a "conveyor belt," which moves the dropped block to the printing surface. When it reaches the surface, it turns into solid concrete and is pushed into position. This is repeated until the print is complete.