RepRap Yo-Yo

60 hours to print a Mendel, or 20 for a Micro Mendel is a Long time. Eventually you get sick of watching the printer print. You have 624 bearings, you have M4 socket caps, you have m4 bolts. Why not build a Yo-Yo?

Design file in HeeksCAD included, Boolean has not been done in design file so you can easily alter the design.

I have got it to return only once, but I am a dunce with Yo-Yos. Can you make it work better?