Probably should have taken more pictures while doing this, but there are lots of guides and videos online, so just do a quick search and you will find tons of great guides if you wish to make one of your own. I made mine out of a huge soup can. One of those wholesale ones at Walmart, which I guess puts it more in the realm of a coffee can forge.
It’s made by drilling mounting holes and a burner hole in the can and mounting to some sort of board. Then the inside of the can is lined with a 50-50 mixture of sand and plaster of perris, in a barrel shape on the inside. This isn’t the best choice of lining and will break down over time, but it’s really cheap and available locally. Then, insert a swirly torch and let it run for a while to dry and cure the plaster. Then you’re ready to forge something or heat up glass for blowing or whatever strikes your fancy.
I will be putting a door on this at some point because I’m impatient and want it to heat things faster, but that’s optional. It does function well and will get things really stupid hot without any door. Oh, and do be careful running this indoors as it will produce a lot of carbon monoxide. I use a shop vac and a makeshift vent hood to suck all the exhaust outdoors.