[Qbot2640]

It may be too late for this suggestion, as you have already put a considerable amount of work into drawing your pvc structure, but I would build this from electrical conduit rather than pvc. It is much smaller, a bit lighter, and even 1/2" conduit is considerably stiffer than pvc. Plus, with conduit you can carefully wrap whatever color of duct tape you wish around the pipe to make a very durable colored piece...pvc can be painted, but scratches if you look at it the wrong way.

I bet you could find CAD files for all the fittings from McMaster Carr.

Oh - one downfall - there does not seem to be "T" fittings for conduit, so you'd have to make something yourself.