This build uses very few tools and even less material. The end forge is created from a single fire brick, some bailing wire and some optional fire proof insulation.
STEP 1: Drill the work material hole
The first step is to bore a hole lengthwise through the brick with a large drill bit (or paddle bit). This hole is the work material hole and will be used to insert metal rod to be heated and worked on. This hole is best if oblong in nature to allow for more height to work with items as you fabricate and should go all the way through the brick to allow working the middle of a long piece of iron. A simple wooden jig is used to hold the brick steady as you drill it out, these bricks are very fragile and may crack easily.
STEP 2: Reinforce with wire
Because of the fragile nature of the fire brick you will want to reinforce the brick with some bailing wire. A single band wrapped and tightened about two inches from each end is sufficient. Tight bends on the wire help keep it snug and tight to the brick. Don't over-tighten the wire though as this again may split the brick.
STEP 3: Drill a hole for the torch
First decide which end is the front of the forge. My choice was simple since drilling the work material hole had resulted in one end being slightly larger than the other. You will want to drill a hole about one inch in diameter to accommodate a propane torch. The hole should be two to three inches from the front and only intersect the work material hole. Do not drill all the way through the brick.
STEP 4: Heat stuff up!
At this point the forge is complete. You may wish to craft some simple blocks to set the forge on or to balance the torch (to keep it from rolling around). The wood block pictured below helps to insulate the forge as the metal table I was working on would act like a massive heat sink and cool the forge.
Here you can see a crowbar in the making ( looks a little like rebar if you ask me ).
After the metal rod has been in the forge for a few minutes just place it on the nearest anvil and coax it into shape.
A bad photo of my favorite crowbar...
MAPP gas can be used for higher temperatures.
A couple of doo-dads made in the forge.
If you are doing a short piece like the crowbar end I did, shove some fire-proof insulation in the back end to trap more heat.
Thinner material, such as 1/4" rod, is more appropriate than rebar for this size of forge. Rebar has quite a bit of mass and is hard to heat up without a considerable amount of time and effort.
I plan to encase my forge in concrete to make it a bit more durable. Without some type of strong reinforcement I doubt this little guy will last long in the workshop.
I need an anvil.
As always, be safe.