What is Independent Dual Extrusion 3D printing? Independent Dual Extrusion (IDEX) means that the 3D printer consists of two separate tool head carriages which allows independent, simultaneous movement during printing. The separate tool heads prevent the residue drip often found in traditional single toolhead configurations. With both hotends working simultaneously, capacity is double that of a conventional desktop 3D printer. This translates into double the productivity with the same investment of other 3D printers.