This is your opportunity to try something different. Green, blue, white, or as a friend of mine did, real Gold. It doesn't take much and wasn't that expensive.
I bought a package of toothbrushes in assorted colors at the Dollar store and whittled a new insert using an exacto knife(I used the red one, but had the choice of orange, yellow, green and purple too)
I would recommend the Brownells front sight insert kit. It comes with yellow, red, orange, white, and green powdered pigments that are really bright compared to most any epoxy and Testors model paint combination you may use. Its not nearly as important to get the mixture just right with the Brownells kit, its very forgiving. The Brownells stuff smells a whole lot better than any epoxy or casting resin I have ever used. And last but not least, it sets up in 30 minutes compared to epoxy. All 2 part epoxys I have used never really harden with paint mixed in there, and when it does set up it takes a day or more to fully cure.