The mill is an X2 "mini mill", manufactured by Sieg and imported and sold in the US by Harbor Freight, Grizzly, etc.
The milling vise is a small screwless toolmaker's vise with clamping slots, sold by Little Machine Shop, Shars.com, etc.
Step 1: The design
I'm making the clamps from some scrap angle iron. The stock is 0.25 inch thick. Each side is about 2 inches long (from the outside corner of the angle to the end of the "leg").
Additional stuff that's needed that I'm not making is a T-nut, a flange nut, and about 2 inches of 3/8-16 threaded rod.