Joseph P Robinson
There are TONS of options to use as helmet stands. Antique spools are sold all over eBay. Styrofoam heads abound but I think look poor. Coffee cans, candles and other homemade items can work and can be inexpensive. The idea is two fold.
1. KEEP THE HELMET FROM RESTING ON ITS 100 YEAR OLD STITCHES
2. MAKE THE HELMET KEEP ITS SHAPE/FORM
3. LOOK GOOD
There has been a lot of comments about foam in helmets. The foam is petroleum based and can react with leather or any organic matter. The question is how inert the foam is. Some foam reacts in 3-5 years, some not in a long long time, and some very quickly. Watch to see if the foam turns brown as oxidation is the key. If in doubt or to be safe you can cover the foam with linen or (gasp) tin foil.
Most stands fail somewhere. This is what I use. I buy these. A plastic base. Plastic rod of any desired length. A Styrofoam half head. I think heads fail #3 above.