Snoopy1
640cc Uber Pimp
This is what I ended up with. After fiddling with bracket and supports and sponge and flaps so that the air tanks would stay in place and not rattle it looked like a mess and not workable over the long run, and was, starting to get heavy. Scrapped that and build a box from 1/16 balsa. Made the just so that the air tanks could be slid in and out. Best of all it turned out less weight than all the supports and sponge. That does not happen often.