Double Decker Bus & Chassis (Parametric)

Update 12/4: Added STLs for smaller, thicker bus. (See below.)
Update 12/4-b: Updated OpenSCAD -- fixed some bugs, added some parameters. (10 d/l)

A friend of mine posted a cute metal double-decker bus toy, and I thought it would make a great 3D-printed toy. Using the photo as a rough guide, I modeled this bus in OpenSCAD. It's parametric so you can change things like the overall dimensions, thickness, wheel sizes & offsets, axle sizes, rounding, window height, stile width, trim height, an