smars chassis blank

Blank to fill the windows left open between the [SMARS modular robot](https://www.thingiverse.com/thing:2662828) chassis and the control board which is useful for mounting through switches, LEDs, etc... You can drill/cut holes as desired or pop the provided FreeCAD projects open and model them in. For convenience, I provided a blank with a 5mm hole which was the whole reason I designed this part.