This is a mini forge that I made out of six firebricks. It is usable to me for the little things that I am trying to do. The nice thing about it is that it is portable and inexpensive and allows me to work cleanly. It was also easy and inexpensive to make and the bricks can be reused. I used Oxy/Acetylene to heat it.
The first test of this forge was restoring a rounded off hexagonal lathe chuck wrench. It was almost fully round instead of hexagonal. To fix it, I heated it up, upset the hex part slightly (made it thicker), and then forged the hex shape again. To make sure that it is the right size (1/2" hex), I inserted it into a 1/2" socket, where it was found to fit snugly after a couple of adjustments.