You can use a plumber's blowtorch to heat the dome for raising and planishing. It'd just take a long time. 
As with all things: cost, time, quality -- pick two. Make a form to shape around using the modded WOF templates to determine the shape -- basically a lopsided truncated cone. Ish. I have a posterboard form for my sintra helmet and gauntlet test-builds:
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In the back, there, on the left.
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First attempt, since revised (but, as with all my more recent pics, the images were on the hard drive that died and haven't been recovered yet).
These might even work for the metal pieces, too, as I will use rollers to get the sheet metal to curve, get it fitted to the shape as closely as possible, then cut and weld/braze. But I'll most likely use these to make moulds from and make shaping forms out of hydrostone or some such. A forge would be nice to put the finished piece in for annealing once everything was joined, to relieve stress/fatigue, and having a heat-resistant shaper to stick it on as it gets more malleable would probably be a good thing...
I just wish I had th eequipment to do this. 
At this point it's just planning and patterning and preparing. *sigh*
--Jonah
