I am building a boiler for a 3" scale foden and have made the plates to form all the 1/8" thick copper. I have also posted on Homemadetools.net a tube strightening tool to un-coil 3/8" 20 gauge copper tube for the 63 x 9" long fire tubes. Please view link below for photos of formers and plates.
The boiler is well under construction so hope to start silver soldering very soon.
Thank you for viewing.
The Home Engineer