Player armadillo armor (to roll into a ball)

I love being able to traverse 1-block tunnels using the crawling feature but using trapdoors to get into the state is a bit clunky -- what if armadillo armor could be made for the player that allows them to turn into a 1 block ball to roll around? This could make for interesting parkour and puzzle maps as well. While rolled up perhaps players cannot hit or build in order to balance it for pvp?