Ok, I finally made a couple. I found the closest metal to the original, which is zinc plated 0.5 mm thick is the thin sheet metal case of computer power supplies. The dull, bluish-grey, zinc coated, sheet metal power supply cases work well.
They cut easily with tin snips, are the right type of metal, and are exactly the same thickness. I used a tiny jeweler's file to clean it up after the photos were taken.
However, if you notice, I altered the design a little bit so the hinge curl is supported at both ends. Hopefully this will prevent the hinge from breaking.
I had to design a very precise timer for the spot welder in order to get any kind of control on the weld.
This is one of two. I have photos of the other one mounted, but I'll have to dig them up later.