Abstract: A novel machine tool featuring a rotary tool changer is disclosed. In one embodiment, the tool changer is pre-tensioned, preferably by a counterweight, to improve repeatability when shifting from one tool to another. In another embodiment, the machine tool is principally a 3D printer, and features a novel cleaning mechanism that improves print quality, especially when printing elastomeric materials. In another embodiment, the machine tool features a rubbing tool that is heated and passed over the surface of a workpiece to improve the smoothness and precision of the workpiece.