I put together a tower for 29mm rockets today. $10 actually gets you a decent tower. I took 3 small "channels" (don't know what they're called, please tell me if you know), drilled them into a 3/4in PVC coupling and attached it to a 1/2in PVC tee. It's pretty sturdy and doesn't give the rocket much friction.
I still have to figure out what to use for a blast plate.
need to add more screws here
With a 29mm CF tube
loaded with the mach-mobile