So I'm on a budget and I'm trying more advanced things with my figure painting. I'm putting the finishing touches on a figure that I'm entirely repainting and I was wondering if using nail polish top coat as a paint sealant would work. I'm using Testors Acrylic paints if that makes any difference. Note- I don't mind if the finish is matte or glossy or whatnot.
Don't do that! You don't NEED a sealant, especially when using model paint. Whatever you do, get the right clear coat/sealant for the type of paint you are using. Acrylic with acrylic, enamel with enamel, lacquer with lacquer.
nail polish is almost as tough as lacquer, putting it (wet) on anything will pull it up (unless you painted your custom with nail polish of course) like I said in the other post (and DP said) work your way outwards or leve with strengths of paint. Lacquer > Enamel > Acrylic.