I'd like to build a reversible projector screen like this one:
and I'm wondering how you might build the rotating trolley/rail setup.
My first guess is to build the screen and rails out of Unistrut and to add these trolleys to the top and bottom corners of the screen (four in total):
If I go this route, how should I build the pivots that allow the trolleys to turn as the screen reverses? Could I get away with running a piece of threaded rod up each side (from the bottom trolley to the top one on each side of the screen) and then… add a pivot somehow?
Maybe screw a cylindrical standoff around the rod and pair it with a bronze bushing at each corner to allow it to spin?
I don't know much about this sort of construction, so I'd appreciate any advice.