@pierre Thanks, Pierre. I understand that this is difficult to imagine given that you don’t know what it is for. I promise to come clean as soon as I can. A pulley, cams, etc, will not work, needs to be a big spring. When you see it you will understand, and I hope that that will be soon. The spring does not really need to do much work at all, except, with little or no resistance save air and a bit of friction, expand from its compressed length to something close to its full length. For now, it does not need to be durable in cycles, ie it does not need to perform for many cycles at all. For initial testing it does not need to perform any cycles–ie it will be tested at or near its full, uncompressed length.
Thank you again for all your thoughts.