thinking of making a bucket..

Not to cut you down, but I wouldn't recommend trying to build a helmet out of aluminum unless you've had a good bit of experience with it.

Aluminum will be very difficult to make the curves with properly. It's not like you can just buy a few for sale signs and cut them up; aluminum is a metal, and metals are more expensive than wood, Sintra, and cardboard. You're probably talking about 1/32" aluminum sheet here; 1/16" will just be too thick for you to work with, barring proper metal shop equipment

You'd be better off making a dome out of something else rather than try to form aluminum. As for the rest of the helmet, the complex curves will be difficult to match exactly; not that it can't be done, but it requires a LOT more work, since it's a lot harder (and more expensive) to fix bad bends in aluminum than cardboard/Sintra.

While we're on the subject, how exactly are you planning to connect the pieces? You can't arc weld aluminum, you need a MIG or TIG welder to do it properly (if I remember right), and I wouldn't count on Bondo to actually hold well. Cutting the material is another problem; you can do it cheaply with aviation snips (which will distort the edges), and the best way to do it is with a press brake or plasma cutting system.

I would go into detail and tell you which aluminum alloys you should be considering, but I'm not convinced that you should be trying this without a lot more knowledge of metalworking and forming.

and your probably right and im not going to try this ATM but this is on my TO-DO list of things i want to make,trust me there is a list and it rivals the naughty-nice list of santa lmao

It is very hard to do unless your a tin smith ive tryed with very disapointing results. how ever i got good results in the end buy ussing thing gauge aluminium rolled and glued plastic, for the back and the upper and lower checks. But good luck with it.