You can get a very nice finish with a $20 Harbor Freight gun and pigmented conversion varnish. I use ML Campbell’s Envirovar and it lays down very smooth in two coats. It’s not a piano grade polished finish, but it’s better than our better cabinet shops around here. I wouldn’t expect the gun to last more than a project or two but it’s only $20.

I prefer my Fuji mini mite, but the HF gun works fine with a cheap air compressor.

Dan