fidget spinner thingy

This is a replacement part for:
http://www.thingiverse.com/thing:2237509

When I was trying to print the spinner in a smaller size (75%), some of the wheels broke off when I tried to get it off the plate.
Another problem with this design is that the center thingy isn't sticking out, which makes it more difficult to hold or to let it spin on a surface.

So after first trying to design a re-fittable thingy in freecad, I did a second attempt in openscad. This design is easy to scale and you c