First, you must acquire two bread makers. One bread maker will become the roaster and you will harvest the heating element from the other. This roaster design requires at least two heating elements to get the temperatures you need to roast coffee.
When selecting your bread maker it is important that both bread makers’ baking bays are roughly the same size. You cannot reshape the elements from a different size bread maker to fit different sized bays. The most common sized bays I’ve found at the thrift stores are roughly 7″ square.
Secondly, you may want to examine the paddle that kneads the bread. A metal paddle will hold up better under the extra heat. It’s possible one of the plastic paddles will be fine. Both versions I built have metal paddles.
I’ve purchased three bread makers from a couple of different GCF Stores. I paid $5 for two of them and $9.97 for the other.
You could possibly get in the roasting game for $10 plus a few other supplies.