A not atypical coffee roaster, like an old-school Probat favoured by Stumptown, looks like this (or this). Not a small machine. Unless you compare it to Dave Hartkop's Helios 4, a solar-powered coffee roaster.
Composed of more than 600 mirrors, it's around 5000kg and takes up over 93sqm. Sounds crazy complicated, but the mechanics are simple enough: The mirror array focuses sunbeams into a receiver box where the air inside's heated up to 482C - solar-powered fans blow that air into the roasting chamber. While all that's happening, the roaster makes sure the array's lined up properly by watching a camera feed of the sun, adjusting the array along a pair of concentric circular tracks.