This tutorial is based off of the foundry created by the King of Random, though it is a bit more in detail and includes our entire melting set up. By the end of the project we were smelting aluminum cans in seconds. A bag of charcoal lasts us about four or five hours of melting using our set up.

Supplies

Plaster of Paris
Sand (Finer grain seemed to work better [recommend play sand])
Two U Bolts or Large Screws
Steel Bucket or Similar Canister
2.5 Quart Bucket
5 Quart Wide Mouth Bucket
Sand Paper or other Sanding Instrument
Hole Saws
Steel Pipe
Duct Tape
Shopvac with reverse function (Or other air blower)
Heat Resistant Gloves
Crucible Tongs
Crucible

Step 1: Building the Insulation in the Bucket

Use the 2.5 quart bucket as a measuring tool. Add 1 3/4 bucket plaster of Paris, 1 3/4 bucket sand and 1 1/4 buckets water. Mix until the solution is totally fluid and there are no longer any chunks. Then, stick the 2.5 quart bucket in the center and push down until the top of the bucket is flush with the inside mixture. It helps to fill the bucket with water which adds weight and prevents it from shooting out. Leave it for a day or two until it is completely dry.

Step 2: Building the Top

To build the top, add half of the ingredients that were used in the previous step to the wide bucket. Mix thoroughly. Then, stick in the U bolts or large screws which will act as handles. Add them closer to the edge of the bucket than the center. Make sure that when they are lifted upon, the lid will also lift and won't break. Leave for a day or two to dry.

Step 3: The Hole Saw

Use a hole saw that has a diameter wide enough for an aluminum can or whatever else you desire to melt. Use it to drill a hole in the center of the lid.

Step 4: Sanding

Depending on the crucible, it is likely you will have to sand down the sides of the bucket. We recommend using charcoal briquettes. Make sure that the bottom can be coated in briquettes and when the crucible is placed on it, the lid is still flush with the top of the insulation. A briquette should also be able to be placed on every side of the crucible otherwise all your time will be spent refilling the foundry and none melting. Try to avoid taking off an unnecessary amount of siding or the insulation of the heat will suffer.

Step 5: Airway

To create an airway, use another hole saw to drill through the pale and insulation at an angle so that if the crucible breaks or overflows, liquid metal will not leave through the hole. The hole should be large enough for your steel pipe attached to the shopvac to enter.

Step 6: Starting the Fire

Use some fire starter or similar material to start the charcoal. Once it gets going, add your air pump. For our shopvac, we covered the air intake with 7/8 with duct tape until we had a desirable air flow. It may appear that the charcoal has gone out if the air source is high enough, but leave it for a minute or two and it should come back a bright yellow-orange and hotter than ever. At this point, leave it for five or ten minutes to heat up and then add the crucible. Add charcoal around the crucible and let it heat until the crucible is orange at the bottom. Cans can then be added to the foundry.

Step 7: Melting Cans

Be careful! Everything including the handles are extremely hot at this point. Wear a face shield or at least glasses to prevent charcoal from flying into your eyes as well as heat resistant gloves. Also, some of the cans smell incredibly toxic when they melt so be careful there too. Place the cans in through the top with the crucible tongs and let them burn/melt. Every ten or so cans, be sure to clear the slag off the top. If the foundry is hot enough, the only solid should be slag and it is easy to scoop off the top of the melted aluminum. We used the crucible tongs and then dropped the slag in a steel bucket. Refill the charcoal as it starts to burn out. Refill the charcoal at the bottom every other time and life the crucible enough only so that charcoal can slide down the side and into the bottom or it will lose heat fast outside the foundry.