For the metal parts, I'm used something suggested in the Matters of the Force "Costuming on a Budget" panel at DragonCon: cookie sheets. I cut out eight pieces from one of those very old, thin cookie sheets: seven side plates and one pointed one for the front of the belt. (Hint: Never cut out metal in a small, enclosed space.)

The round parts on each belt plate are made up of 1 1/8" button covers. The pieces are glued to each plate with the shank passing through a slit. Velcro on the back of each piece (two strips, one above the shank, one below) holds the plate to the vinyl. The end of the shank passes through a slit in the vinyl. Part of a hair pin slips through the shank, and the ends are hotglued in place.

To keep the belt closed, I used no-sew skirt hooks I found at Hancocks. I probably should have placed two on the belt edges, one at each corner, instead of just one in the middle. However, I think it'll still hold together fairly well, and this way the hook is hidden underneath the center back belt plate. (It's the only plate not held in place with hotglue and a hair pin, just velcro.)