Necessity is the mother of invention.

[Frank S]

When I was stationed in Germany in the mid 70's there was this one German local who didn't have an air compressor but would touch up the paint jobs on cars in his garage he would haul a couple of truck tires at a time to the local service station until he had enough of them to use as an air supply for his job if he ran out before he finished he would use the oxygen tank. seemed to me that it would have been cheaper to just buy an air compressor