Parametric Mount for Berd Air MAX

Here's a simple OpenSCAD-based mount for the large motor used in the [Berd-Air MAX system](http://www.themakerhive.com/shop/viewitem.php?productid=45). As opposed to the mount published by MakerHive, which seems to be optimized for aluminum extrusion-based frames, this mount is intended for Prusa i3-style or boxy CoreXY printers with frames built out of flat materials.

The motor is held in place with a strip of double-sided velcro (a few zip-ties are too puny to handle this gigantic motor), w