Crank arm which fits onto LEGO (R) Technic cross-shaped axles. When assembled correctly, the round handle part spins freely on the M3 screw which is fastened to the crank arm.  SCAD file provided so you can make a different crank arm length, handle etc.It took me 8 iterations to get the "+" shaped socket to be a snug friction-fit on the axle without being too stiff. The file has been tuned for my printer (UM2, PLA at 20 mm/s, 223 C) and may need adjustment for a perfect fit with any other printer.