Had fun doing this, Took me ages to find the perfect dome. It was a clear plastic packaging of a ball I found in a store. It's slightly soft but still hard enough as a helmet for this armor.
Other than the dome and the I'm head, this custom is made entirely from an Iron Monger figure. I sculpted a few extra light source on his body, effective only for underwater exploration lol.
Unfortunately it's not water tight so Tony Stark still needs to do some work in this suit. hehe...