This instructible has no photos, only drawings. This unit I Built in the late 70's for melting aluminum transmissions, bumpers and such.
The unit was about 4 ft square and 6 ft tall, would accept whole transmissions that that had been drained of oil, and automobile bumpers thru its 36" feed chute. the continuous flow of molten aluminum was poured into 1/2 ton molds.
The burner unit which is the main focus here can be scaled up or down for your particular needs. This size unit when burning uses about 7 gals used oil an hour, at 20,000 btu per lb, that's equivalent to 1.12 million btu an hr. much more than most garages need.
A 1.5" x 12" unit was placed in a barrel stove in a garage, it produced as if the barrel stove was running wide open, and burned thru in 5 mins because there was no fire brick. So be careful and have fire extinguishers handy, if you decide to build a unit like this.