Body work nostalgia is an interest of mine. One of the most interesting aspects of the early automotive era was that minor body and paint work was actively pursued by service stations, and many specialty companies existed that marketed "quick fix" tools to these small businesses. One of those tools was a "portable" touch up spray gun that could be powered not only with a compressor, but also could be attached to a valve stem on an inflated tire on the vehicle to do touch up. Many of these kits were sold to the DIY crowd and small garages to increase their profit margins. It's important to remember that air compressors were not cheap in those days, and many small service stations and especially hobby mechanics didn't have shop air until affordable portable compressors became available after WWII.
Another interesting product for the "professional" body shop was the lead spray gun. In the days before polyester filler, lead was used to fix car bodies, and these guns melted lead bars and sprayed the melted lead through a special nozzle to build up layers on hot lead on a body panel.
Needless to say, health concerns about airborne lead particles and OSHA standards were not existent at the time. These things were dangerous -- not only from the fumes, but also from the amount of hot melted metal you held in your hands.
