I find that in making dies, I spend at least as much time just squaring up my components as I do actually drilling and machining features into them. I buy premade flat ground stock whenever possible, but for many of the sizes I work with, I have to buy oversize material and then saw/facemill/surface grind the items to size and to square up the sides.

Does anybody know of a supplier that sells surface ground, squared (up to all 6 sides) blocks to spec - and that does so with short timeframes?