I already have a PowerSpec Ultra 3D printer for 9 months. A drawback is the build volume of about 9 inches by 6 inches by 6 inches. Someone built a larger 3D printer using parts from a smaller 3D printer at http://www.instructables.com/id/How-...g-a-Smaller-3/ He printed out the frame instead of buying aluminum extrusions. I would use aluminum extrusions but I don't know the size of the lead screw used for Z-Axis. All I need are longer guide rods, longer GT2 belts, and longer lead screw. Any suggestions?