FYI, I made a discovery years ago that may help in this project. Aluminum stock when formed into a curve, perty much retains the curve indefinitely. So knowing that, I made the springs for my 8x10 contact printer from 1/2"x1/16" aluminum stock that I purchased at Lowes (or Home Depot). I simply created the two springs with a slight curve by forming them around a large bucket. The contact printer frame itself was made from a solid wood picture frame. It still works like a champ. I can post a picture of this contraption, if desired.
This will depend upon the particular aluminium alloy and what temper it's supplied in. Some alloys/tempers are like butter.