Do you have or have access to a small 90* air grinder? If so you could use the rol-loc discs made by 3M. The gray unitized wheels. I am sure you could use them in a straight die grinder too. It would just be a little harder to control.
For the dremel. I would think the cotton wheels with a little polish would shine up the material pretty good. I would get the surface down with something else first. Maybe you can get your hands on some cotton seed bits. They're different from the cotton discs for the dremel. We use them at work but, the ones we have on hand have a 1/4" shank.
I guess if all else fails you could spend some alone and intimate time with your project and hand sand it with various tools.