NEMA 23 Protective Shaft End Cover

After getting jammed in the kidneys with the protruding shaft on my CNC machine's NEMA23 stepper motors, I cut down some half liter water bottles to cover the end of the motors. They worked somewhat, but got knocked of easily and I finally decided I should do something more permanent. Hence this design. I made four to use on all 4 motors on my machine. The two in the the front (the Y axis motors) were the ones I would bump into, but there is also the issue of bending or having something gett