Ed Bourgeois built one of the finest home roasters I’ve ever seen. Here is a list of his requirements:

1kg.+ electric roaster My goal was a roaster that could do at least 1kg green. with electric convection heat. I mainly wanted the abilities to:
1. control and monitor every function
2. remove the chaff as produced into an external container
3. create a fluidbed action with the beans but achieved mechanically rather than with heated air.
4. dump and cool in a minute or less
5. must roast very evenly
6. ability to add conduction heat when desired
7. ability to imitate various roasters
8. built with durable and dependable components
9. safe to use

And here’s how he did it:

• A) Variable speed convection fan 0-5600rpm
• B) High/Low range convection fan toggle
• C) Main heater On/Off toggle
• D) Beanbats speed control
• E) Chaff canister
• F) Roasting pot
• G) Boost heater control
• H) Main heater and fan
• I) Tilt dump
• J) Bean temp. thermocouple
• K) Air temp.
• L) Volt/Watt digital display “Kill A Watt” meter
• M) Variac 0-140v for main heater
• N) Timer
• O) PID
• P) Cooling drawer- removable cooling tray
• Q) Base with Beanbat speed control gearhead motor 0-330rpm
• R) Dumping handle in back

Read more about it here.