I took two old 20 lb propane tanks and hooked them together with soft copper pipe.
Then I put a quick coupler on the end of the plumbing.
When I need a lot of air I hook my little compressor to the tanks.
This cuts down on the on/off cycle for me.
I'm using a Campbell Hausfeld I received as a gift. It's worked good so far.
Good enough that my part-time roofer friend likes to borrow it.
Part-time roofer and part-time friend. Friend when he needs to borrow.