Helmet sizes : Can a helmet somehow be enlarged ?

[Hibernicus]

woodworker bench vice...
http://images.rockler.com/rockler/image ... 01-200.jpg

or a press screw / shoulder screw...
http://images.rockler.com/rockler/image ... 01-200.jpg

or a front vice ...
http://www.timbecon.com.au/assets/image ... tbfv-1.jpg

mechanics / engineers / bench vice
http://www.blackjacktools.com/pcat-gifs ... es-002.jpg

Clamping the helmet into this type of vice, smacking the outside face of the jaws.. hard!.. with a heavy hammer...

The wood workers bench vice works well for pressing a hot or annealed helmet dome. Back in the day when we made our own helmets from 11g/12g domes we'd press them in a woodworkers bench vice

[M. Demetrius]

I'm sure any of those would work (audible pun cue) but what I was thinking about was these:

http://www.harborfreight.com/cpi/ctaf/D ... mber=92446

Anything would do, though, to provide pressure. A foot will, but it's harder to control...just a little too much, you crimp the metal, then the repair work starts for real.