Published at Monday, August 13th 2018, 22:19:51 PM by Nettie Ross. Air Compressor. A portable air compressor comes in many shapes and sizes. We are only truly portable if we don't get too big. As long as we can be moved around easily and used where needed then we are considered truly portable. Once we get too big, then we are relegated to shop work and other stationary jobs. I pity these poor fools. It would be boring to just sit in one shop all day. I like getting out and seeing different places and meeting different people. I think it keeps me young.