One of things I really like about OpenSCAD is how anything I make in it is guaranteed to be manifold.  It’s a solid modeler and by manipulating, adding, and subtracting solids – I should always end up with another solid.  I exported two of the parts necessary for a Pez Powered Disc Shooter only to discover that OpenSCAD refused to compile one of the parts – because that part had some polygons with an incorrect winding order.  Mind, I had no problems exporting the part in the first place – but importing it back?  Nope.

Oh, OpenSCAD, is our love affair over so soon?