I posted in a thread about Dave Berten, and having given up on my order, for springs and screws, etc, the main thing I wanted was a clock spring, and others. Having now given up waiting, I've sourced all the screws elsewhere, yet to arrive, so I don't know if I specified them correctly, but I'll find out.
For the springs though, I picked up some various piano wire and have tried to make my own. Yet to tackle some of the smaller ones needed, but thought I would try the clock spring first. Not the prettiest spring in the world, but it seems so work. I got 1m of 1.22mm wire, says size 22 on the bag, and I was short by about 5 turns, on my planned length. I'd calculated that 1m should be enough, from a spring calculator I found, but obviously I made a mistake, or my mandrel was a bit thicker than I thought.
I got close to the 40 turns I was aiming for, but that's all I could do from 1m, and then I struggled to bend the ends on, and lost some that way. However, it seems to work, and even if not perfect, it's a damned sight better than the multiple elastic bands I had been using.
https://youtu.be/mZSSJdMczug