Materials I used:
Bathroom exhaust fan ( these fans suck air rather than blow air). Diameter 25cm (10").
Bucket or other container - the top of the bucket is slightly smaller than the fan.
Aluminium Ducting - I used 150 mm diameter x 3.6 metres (6" x 12').
Duct tape.
Utility knife.
It's best to buy all the materials together to ensure the fan fits properly on top of the bucket and that the bottom of the bucket is wider than the ducting's diameter.
The fan cost $30, the ducting $28, and the bucket just a few dollars