something nobody has mentioned is what about an air tank with a quick change coupling and a filter dryer. just hit the gas station and tank it up. Years ago (B.K. - before kids), when I used to build models, I got a couple old freon tanks and put a couple air tank adaptors on them and used them as an air supply for air brushing. Why couldnt you do the same thing with an automotvie air tank for inflating tires. Throw em in your vehicle and hit a gas station (especially if any still have free air) and tank up. We also used to use em as a portable air source for tires, blowing out bug lights, etc. When using any air source you want a dryer at least to filter out any moisture from the line before it gets to the brush.