This is the first time I've attempted to make a live steam boiler so this should be interesting. After all the reading I've been doing, I decided to try to build it using some of the methods that I've read about. This will be a vertical boiler using a piece of 2 inch type L copper pipe for the boiler shell and flue sheets. I cut the boiler shell piece off the pipe at about 8-1/2 inches and then cut another piece off the pipe about 2-1/4 inches long. I cut the short piece onso that I could roll it out flat and then annealed it with the propane torch using Mapp gas. It's much easier to bend after that. 
I found that you can cut pretty thick copper sheet with heavy duty tin snips to rough in the outer corners of the circles for the tube sheets. I cut the circles away from the sheet with a coping saw, trimmed them as best I could with the tin snips, and then filed them to fit inside the pipe, with a slip fit.
http://www.flickr.com/photos/amber_darlene/6804821456/
I found that you can cut pretty thick copper sheet with heavy duty tin snips to rough in the outer corners of the circles for the tube sheets. I cut the circles away from the sheet with a coping saw, trimmed them as best I could with the tin snips, and then filed them to fit inside the pipe, with a slip fit.
http://www.flickr.com/photos/amber_darlene/6804821456/
