The Poplite popcorn popper I’ve been using as a coffee roaster lacked even a simple power switch. I ordered a couple of suitably-rated toggle switches and wired them in to control the power to the whole shebang as well as to switch off the heater while allowing the fan to keep blowing. This should (1) allow for cooling of the beans in situ and (2) help cool the device between batches to prevent the thermal cut-out from kicking in.
The wiring inside the popper is really simple (check out the diode bridge around the DC blower motor) and I managed to wire the switches correctly by just eyeballing the scene. Looking forward to using it. By the way the chimney extension I made out of sheet metal works nicely.