About this 3D model

A toy marble/car gravity thing. Put the car (or marble) at the top of the ramp and gravity does its magic. I as yet have not made this as I am waiting for the parts for my CNC machine to be delivered (repairable machines - http://www.thingiverse.com/thing:9182). Full source files attached. Alas at the moment the full model is not manifold, but when flat=1 or 2 or 3 the parts, (Which I plan to cut using my CNC) are manifold. Not made yet.