Exactly my thoughts on choosing lowryders. 4ft x 4ft is pretty easy to knock up for me. Will have to make the box in situ because the opeing is so small.

Nochowder any ideas on yield??? Gonna be using a CFL but not sure what wattage I thought 250w but can only find 150 or 400. I have read up on this but just wanna be sure.

The biggest problem I can think of is ventilation and temperature because the attic gets very hot in summer and very cold in winter.