Bodgers gotta Bodge
The first thing I did wrong was point out why his original design wouldn't work. The second mistake was trying to do it with materials to hand rather than getting him to cough up the cash to buy some aluminium or steel tube stock to make the damn thing properly in the first place... but I'm getting ahead of myself here.
OK, a friend with a old Graflex medium-format camera wanted to build a mount for an oddball camera lens he had kicking around, a Kodak Aero-Ektar lens from a WWII aircraft reconnaissance camera. Those of you in the know will be backing away at this point but really the lens is not VERY radioactive, and only the back element has lots of thorium in it. The front element is probably harmless. The upshot was, after a certain amount of sucking of teeth and doodling on scraps of paper was Rule 1 (see above). After that it got messy, involving hacking with the big angle grinder on some 1/2" thick steel plate following by machining away 90% of the resulting blank, relearning how to cut threads on the lathe (3" diameter 24tpi), laminating and boring slabs of oak planking, drilling, gluing, screwing, cursing, swearing and bleeding. Here's the result.
Knowing what I know now I'd have done it differently and if I ever did it again I'd make a better job of it. But see Rule 1.