Parametric cup stacker

Loved the original model, but was struggling to find the right scaling for my glasses/shots/cups. This parametric model makes it very easy as you can create the model in a single line: cup_stacker(top_r_out=30,top_r_in=24,bottom_r_out=30,bottom_r_in=24);

Moreover you can have different sized cups stacked on top of each other as well (since you can control the radius of the bottom part, and of the top part)

See the image for the meaning of the parameters.

I ended up creating a robust version since the arms were a little bit too narrow for my liking. I'm leaving both versions since the code for the robust one is a little bit more complicated.

Made the model parametric.