I used to use Tamiya to "improve" a bunch of my old GI Joe toys, and it always rubbed off with handling. On models, I find that it too rubs off and scratches easily. But aside from building it, how much do you handle a model? Just cover it with a clear coat and you're set. Depending on what plastic you're working with, you may want to prime it before painting with Tamiya. I find that it never wants to stick to the plastic Dragon uses.