Hi Cathy -
There are a couple of products you could mean. Annie's Soft & Stable is like a cloth lined foam that makes bags stand up. That would make a comfortable helmet that would stand up pretty well. For the bill, you might want Timtex, which is much stiffer and is designed for hat bills and fabric bowls. Or if you want a very stiff stabilizer, DecorBond is something that I use in bags a lot, too, to give them body.