I've been waiting for a question like this to pop up. I've been teaching courses on this very technique for years. I started out using the Dreve products but the gum "glaze doesn't work long term. It has a tendency to break down and start to peel off and discolor. Heraeus Have a range of great light cure options, simply treat the surface of an unpolished denture and paint away. The finished result looks great and is only limited by your artistic skill. This won't peel off because you actually add a layer 0.2mm or thicker if you want. You can actually even do some surface characterization like stippling in the material before you finalize the case.
If you are nervous about light curing then Look at the Anaxdent products they are FANTASTIC!!!
ACRYLINE With these products you can either do the light curing option which can actually be used in the mouth. Or there is an acrylic option, where you use a wet brush technique to add a thin layer of colored acrylic to the surface and pop it in the hydroflask. Polish as normal, and again you have heaps of artistic options with intense colors to subtlety vary the colors to suit. All the light curing options require a good light curing machine. Skimp on this at your own risk. If the materials aren't cured properly you can have problem in the future. The least expensive option is the acryline products. These products, both the Heraeus and the Anaxdent products are available in the US.
check them out it is worth a look.