A few weeks ago I built a small electric furnace for melting less than 10 pounds of Aluminum. I got the elements from e-bay and bought the firebrick used. This is actually the second one I built, the first one's brick had been damp and crumbled when I heated it up. I cut the bricks for the shell and the grooves for the elements with a table saw. It's wired for 240 volt and draws about 14 amps at 3200 watts. I was able to melt 3 kilos of Aluminum in 40 minutes and about the same amount of Brass in an Hour. I'm working on some type of temp control, right now it's off or on.
I used it to make a tool holder for my little CNC machine, it worked very well. I cut it from pink foam and poured it using the lost foam method.