I decided to try enamel painting with very small model micro brushes. I bought a Testor starter set at Michael's Craft Store (with a coupon of course) for under $20. I will warn you there are a multitude of flammable and "cancer causing" chemical warnings on the front. Maybe OK for teens and up only? I'm sure spray paint has the same warnings but we still use it in moderation so I'll leave that call up to you. Upon further research, you can also use acrylic based paints on 3D plastic with a primer and sealant. The good thing about the enamel is I didn't do either of those things in an effort to save time. I'm sure primer and sealant have a bunch of warnings on them too.