Designing a piece of art such as this requires being able to look at the model—here made of an unsightly conglomeration of resin, acrylic sheet, copper wire, metal eyelets, and brads—and see the finished horn, in all its beauty. (You do think it's beautiful, don't you?) That is the wonder of resin casting, and especially cold cast metal casting.
Cold cast is nothing more than mixing a very finely ground metal powder (in this case aluminum) into resin. Once it has hardened, I sand the surface of the casting to reveal the aluminum beginning with 180 grit, and continue with finer grits all the way up to 0000 steel wool.
The final step is polishing the piece with a Dynabrade rotary buffer, using a foam pad and compounding liquid. That final polishing is the key to getting it to shine.