The most common type of home or hobbyist 3D printer is the Fused Deposition Modeler, or FDM type of printer, which works by melting a plastic filament with a heater element (the "hot end") and extruding the melted plastic out of a small nozzle, much like icing a cake.

Current hot ends can only handle one filament at a time, so the types of 3D printers that can handle multiple colors require a different hot end for each one. This causes a number of problems: the nozzles must be exactly the same height from the work surface, or they will damage each other's work; the distance between the nozzles must be carefully calibrated and the printer's software must make corrections to keep the output in the same place.

The Diamond Hotend developed by 3D printing specialist RepRap.me addresses many of these problems by combining three heating chambers with a single nozzle to create a new sort of 3D hot end that can extrude different colors.