Balance Board

Creates a rounded half-sphere with mounting holes
that can be screwed to a board to create a balance board.

There were other similar models on Thingiverse when I made this, most notably [Ankle Board](http://www.thingiverse.com/thing:28251), but I didn't like having the screw in the top, since this is the primary balance surface.

I also wanted to be able to scrunch the rounded shape, since [some highly regarded brands](http://www.thesurfzone.net/store/product/cat_0/id_40/) count their flat