why not just order one of the aluminum replacement frames from brownells... they are offered in traditional glock angle or a 1911 grip angle.
This is what I was talking about. I believe only the first production 26s were available this way though.
Head to your nearest Marine supply store or boat dealership and ask for some Marine Tex epoxy. Clean off the frame really well (dishsoap works well) and use masking tape to define borders. Mix the epoxy according to the instructions and apply it to the area you want to be smooth. Let it dry and one it's cured you can sand it like wood to get a nice smooth texture. Try to avoid air pockets which may result in craters once you sand on it.
It's not going to be the prettiest Glock in the world but you'll have what you want and the epoxy is tough as nails. You could have the frame coated with DuraCoat to to help clean things up a bit.