I had thought about checking the goodwill and 2nd hand shops to find an old bean bag chair cheap that I could rob of filling, but never got around to it. I would love to know what the weight difference really is between the poly balls and dried beans of the same volume. I designed my large bean bag so it took 12 pounds of beans to fill it whereas other designs of the same size take 16 pounds. If I could get that weight down to perhaps 8 pounds using poly balls, that would effectively cut the normal weight in half compared to similar sized bean bags. That would certainly be worthwhile in practical terms.