Material needed for bucket

I'm starting a scratch built bucket but I can't find the materials that I need. I've decided to use plastic instead of cardboard or poster board. The plastic that I'm looking for is the kind used for "For Sale" signs or business signs, sign boards is what I think they are called. My problem is that I can't find a board big enough that will accommodate the size of the inner and outer bucket. Can anyone tell me where I could find these boards? Does anyone have any suggestions?

Most scratch built helmets are being made with those for sale sigs, I believe they usually run about 18 x 24. I went to a local sign shop and purchased a large sheet of Sintra plastic for $60. (4' x 8'). If you go to the WIKI page, you will find some great tutorials on making one and the materials needed. Also, you can check out Ohld Vart's tutorial at Mandalorian Mercs web site. mercs.firespray.net

Good Luck!
Eric

Thanks dude. Your suggestion really helped me out a lot.

my advice is to use thin sintra (less headaches during construction).. 3mm and up is good for armor though