You will need to make two decisions before purchasing supplies. First, you need to decide how you will connect the wires. Will you use wire nuts or will you use crimped connectors?
Secondly, you will need to decide if you want to install a power switch. It is perfectly acceptable to simply have the coffee roaster start when plugged in.
If you plan to remove the plastic from the stock lid you will need hinges to attach the lid to the cabinet. Small, cheap hinges are fine. You can get a set for under $2.
You will need scrap tin and sheet metal screws. You may have all of the scrap tin and spare screws you need depending on the construction of your bread makers.