If you want to try the non ISO 2k then don't follow mix advertised as its to thick. Mix it 2 parts paint, 1 part hardener and 1 part thinner. But if I wanted to avoid isocyanates I would use upol p88 primer with as little thinner I could use to spray, flat this with use of a guide coat. Then either solvent or water based base coat and upol smart 1k clear. Then just flat it back and polish. I have used this to good effect on some mirror backs. Setting up for an airfed cost me about £200 including coalescing filter, other issue with airfed is air consumption. I can only use a devilbiss sri pro when using airfed unless I get another compressor which for how much I spray is not worth it.