Some of the folks on IFI would like to argue that brake drum forges are hard to build. I couldn't disagree more, my father and I built one in an hour with saw-zaw, drill and some pliers. They take little effort to make and less to refine. In all the guys in my blacksmith organization we have about 45-50 forges, maybe 5 are not brake drum forges and the guys that a brake drum forge as well as a fabbed fire pot, would usually they rather the brake drum forges.
For ME brake drum forges are the best, they're cheap, easy to build, easy to repair/ tweak, and they teach you to use what you have. Yes some forges may burn hotter or maybe cleaner, but for the price I can't beat it.