250 quadcopter frame - one piece (OpenSCAD)

Unfinished 250 Quadcopter design, designed with OpenSCAD, with good math behind it so you can change a lot simply by modifying the variables at the top.

It is still a work in progress, v13, the first (and at time of writing only) version I printed still has the following problems for me:

* sonar holes too tight
* motor holes a hint too tight (but manageable)
* motor cable holes far to big (diamater vs radius..?) [but maybe I'll leave them big like that for cooling purposes]
* motor p