I built my rear bumper as an air tank. It's plumbed into my AC/OBA and allows me to run air tools as well as air tires & operate lockers. Some worry about a bumper being an explosion hazard, and it would be if aired up to 200# or more. My pressure switch cuts out at 120# and the safety lifts at ~140# or so. It's worked well for me, but fair warning... producing 100% airtight welds is harder than it sounds! lol