I have been playing with a cheap old HO scale hopper I am converting to 1/55 for my narrow gauge layout. My attempt at doing Hair Spray Chipped Paint Effect went sideways and I wasn't sure what to do. That was when I got the strange idea of using heat to make my paint job bubble and crack like it's rusting out from underneath. I used a highly prized fine tool for this job known as a Bic Lighter. Sure enough the paint layers started to get an amazing texture. I slightly melted my car. I think the technique can be refined with practice. I have already added a bunch of alcohol and rust particle on top of it and now it really looks beat to crap. I will get a photo of that soon.