This summer I used cellulose paint on the back of my 144, sprayed in my garage using a detail spray gun powered by a cheap 2.5hp compressor. I got the paint made up by a classic car paint company. The back of my 144 was getting a bit ugly: rust on the edge of the trunk lid, and lots of cracks in the paint with rust stains coming out near the Volvo badge. This cracking turned out to be thick, old filler in a dent. Using this painting method I got reasonably good results and didn't turn the entire garage green -- the detail gun was good for minimizing overspray. Made a mess however trying to get the paint thinned down enough for the sprayer -- we now have a green portable heater (that used to be white) with just about every possible paint defect illustrated on it. It was good practice though.