ok i think i can answer you question. i have a few friends that love doing helmets in specific and they love padding the crap out of them. one time they actually upholstered it just like a motor-cycle helmet and other times they put in this spray in foam fabric stuff kinda like felt but it all really matters on how much room you have left and how you intend to use your helmet.for me i am a pro paintballer and i pad the hell out of all the helmets i make even the armor but if i'm just wearing them to be flashy i just wear a balaclava on underneath
I thought of padding it with an old yoga mat that I already cut in pieces, do you think that would be sufficient?