The lease expensive, easiest and fastest way is to pick up a small bottle of Testor's model enamel (about 2 bucks ) at the local hobby or craft store and paint the sight with a few thin coats until you get a solid strong covering. Testor's paint comes in all sorts of very bright colors perfect for front sights of guns. Shoot the gun and see if you like it. If you like it and just want to change colors, all you need is a new single edge blade and some paint thinner.
It will last for a long time, do the job and no big expenditures have been made. If you dislike it you could always put an original front sight back in and all you will be out is 2 bucks and about 5 minutes of your time.
Oh, before I forget, clean the sight well with Alcohol just before painting and use a wooden toothpick instead of a brush to apply the paint. Try to lay the painted surface parallel with the floor while drying and I usually place the gun in the boiler room for a few hours to speed drying. This has worked so well for me over the last 20 years I have stopped cutting the front sight for the liquid plastic that is like the Factory original. There are times I do NOT want a red or green sight - then I can easily and quickly restore it back to the factory black with a new razor blade and some paint thinner.
