Full-face motorcycle helmets make great "hoods", and if you paint one or both sides of the visor, blindfolds as well. None of us are motorcyclists - we recovered ours from our church charity shop. As it was battered, it was no good as a protective helmet so we painted it red and black. Some might say a safer alternative to gagging, as the wearer's voice is muffled but not gagged.
I don't know if this applies to the open design helmets, and ours being a small-fitting helmet will contribute to this, but they get very hot when worn for a while, particularly if the visor is down. Our mother is an A&E sister and on Tuesday this week (the hottest day of the year), the paramedics were called to a house where a 17 year old girl was on the verge of a heart attack because she had tied her younger brother to a deck chair in their conservatory as part of a game and put her helmet on him "for fun" with the visor (not painted) down and left him like that while she was studying. He obviously overheated and passed out because his head was wet through with sweat. Being a total dumbbell, she panicked and rang 999. Once the paramedics took the helmet off and got cooled him down he came round and is ok now. This has been refered to the Police and social services on the grounds of cruelty (albeit unintentional) and neglect.
We aren't using our helmet at the moment!
Gemma