After going through several different designs on the internet, a friend and I decided to make our own Aluminum foundry of a custom design. This instructable is more of a record of experimentation with an (eventual) successful outcome as opposed to a step-by-step with little trial and error.
Be sure to carefully examine each photo and read the highlights, the majority of this instructable is explained and documented in photos. Any and all questions will be answered to the best of the ability, and if we don't know we'll do our best to find out.
This forge is a bit more durable, but much less portable than other models you may have seen, but it can also melt steel should you choose to buy a proper clay-graphite crucible. The ability to melt steel is given to the furnace by adding clay/brick walls to the top of the furnace as seen in step three, no extra equipment (aside from the mud/brick and crucible) is needed.
Step 1: Materials
2" Steel nipple
2" Steel end cap
Charcoal starter fluid
PCV pipe segment (~1.5" diameter)
Slag stick (A long bolt will work)
Proper safety equipment (eye protection, welding gloves, etc.)