Here are my melting and shell heating furnaces. The left hand one is the melting furnace "working on 100 lbs of bronze, the (cooler) right hand furnace has ceramic shells heating in it. Both are heated with propane at about 30 psi, via home built burners both forces air via small (and not so small) blowers. You can see the blower on the cooler, shell furnace. These furnaces are made with KalWool, 2 layers with high temp material on the inside layer of the melting furnace. It looks too hot to touch, but you can do a quick touch of the melting kiln without getting burned, the brightness of the wall material is really the flame shining thru the fibers, it is not "THAT" hot on the outside. The melting furnace was new in this picture, the shell kiln was about 10 years old and a new one was in the process of being built. Cost for both kilns was under $400 for both, with extra KalWool left over for cup covers, hole filling, patching, etc. The units were both lined internally with a kiln refractory made out of zircon and a binder (got it from a supplier in Oakland CA) which gave the interior walls some rigidity and protection from getting torn from shells and crucible tools and reflected the heat back into the furnace. I normally get about 10 years life out of a furnace before I need to build a new one. I can pick up and move either of these furnace indoors with ease by myself. After the first melt, about 1.25 hours from a cold start, the following bronze melts take about 45 minutes each, each melt being about 100 lbs of bronze.

Fully portable bronze furnace.
Smallest gas powered leaf blower I could find - plenty of air at idle.
Stainless cover with refractory slathered kaowool weighs less than 20 lbs.
harbor freight weed burners are way simpler than making your own.

I want to build a speciality furnace. I have the resistor wire. I am looking for the white cement that one sees in kilns or laboratory furnaces. It is similar to pumice. You can cast the resistor wire inside of the cement. Does anyone know what the cement is called and where can I purchase it. Many thanks.