Holy crap! This is a first for me, I dreamed up a way of bending my skins, made the bender out of timber purchased from the Bunnings store put it all together, made a small prayer and got busy with my rattle gun, and it bloody worked first time! Utterly amazing.
The basic setup. The straightest timber I could find, threaded rod plus some quarter round.
The sheet in place with just a little tension holding it in place.
This is how far I wound it down, and it worked out about right after the tension was released.