Completed coffee roaster made from this and that.
Cordless drill holds a threaded rod which holds the steel ikea caddy through a premade center hole with nuts and washers. I added a snipped up tjn lid to the caddy because I was losing a couple beans out the front. I use a c-clamp on the drill’s trigger to keep the drill on and adjust the drum speed.
The enclosure is 2 commercial size cans (tomato cans I took from work) cut up a bit and press-fit together (not glued so I can pull the drum out to dump the beans at the end). Originally I intended the roaster to be open drum over a heat gun but I found it could not get hot enough. The tin can is a fairly tight fit and now the roaster easily gets hot enough to roast through 2nd crack.
Finally, on the bottom thru the tin can is the nozzle of a heat gun that sits firmly upturned (only part bought new). The can actually just rests on top like that and it works ok for me. I cut a strip of aluminum and bolted it on the tin can to mount a k-type thermocouple to get a temp on the bean mass. The numbers have been pretty repeatable.
Total cost under $50 since I had the drill, drum, and thermocouple already.