Update: Added second end cap. I've been carrying my Prusa Mendel by the outside ends of the top bars, and the threads tend to dig into my palms, so I made these snap-on handles. They have a nice curve to them to make them easier to hold, and they also cover the ends. Also, I've seen too many little kid eyeballs get dangerously close to the ends of the threaded rods in demos, so I also made these screw-on end-caps. I have a fully parametric scad file if anyone is interested -- just let me know. 1) Print. The rounded end cap has an internal diameter of 8mm and a material thickness of 2mm, which turned out to be a very snug fit, with a fairly weak wall. The octagonal one is 8.25mm ID with a 1.9mm wall. Let me know if you want to tweak your own settings and I'll clean up the code and post it, too. 2) Install. TOOL CHAIN AND PRINT SETTINGS: For this I used slic3r 0.9.5, Marlin, and j-head 0.5mm with cheap 3mm "repraper" PLA filament (from China). I print onto glass covered with window tint with a thin coat of ABS juice. The printbed is heated to 90 for the first layer (measures about 80 with the IR thermometer), and 75 for additional layers. I used two perimeters, 10% honeycomb infill, and 0.4mm layer height. Hot end temperature depends on color, but is usually around 185.