This is a knob that screws nicely onto the M8 threaded rods for the Z-Axis on a Makerbot. Inspired by Zaggo's, this knob is quick to print.
Print: I made mine hollow with 0.2 infill density in Hex
Install: Mine was a tight fit, but did not require tools
Optional: Press in M3 nut and use screw to secure on shaft