Ive read lots of posts on the forum regarding the size of furnaces and how people cant melt in larger quantities and the cost of commercial models. I used to buy furnaces but some kind soul told me how to create an easily adjustable and cheap alternative. Buy 30 lightweight fire bricks (these are easy to cut with a wood saw) a bottle of propane a regulator some rubber hosing crucibles and a 2 inch torch + gun (i,ll assume you have gauntlets and tongs to protect your hands). Create any size you like anywhere you like all for under £150. If you want to create a perfect furnace it takes a litte effort but you can simply place a layer on the floor stand the bricks on end on top and insert the torch in one corner cut one brick down to stand on the nozzle of the gun then put bicks across the corners to retain some of the heat , from cold to molten metal in 20 minutes. You can melt 20 grammes or 5 kilos by adjusting the arrangrment of bricks.