I was going to save this post until I had nice scans of my design, cost, instructions and notes on making a knife for a file, and some classy pictures. However, the cost/awesome ratio of the paint-can forge caught me off guard.
While my total cost for the forge itself was about $50, it could be brought down to maybe $30 by being slightly smarter than I was, and not buying a giant, expensive torch to light the charcoal.
Here is another post-inferno picture:
Here is a wider-view of the porta-pit. The box of dirt is for insulating a file I am annealing, and the hose is cooling off the forge. The small box of dirt is full of wood ash, dirt, and the file that I heated up to orange.
This thing is pretty awesome. Details on building will come soon.