Id say on the minimum side youre looking at getting (2) 4 foot T5 setup with 8 bulbs..........for max efficiency
So 2 foot deep by 4 feet wide and Id say four feet tall.
This would give you 3 feet tall mommy box and another foot of room for the clones and their light.
But hey thats just how Id do it if I was you.
As a matter of fact Im contemplating a cabinet kit that is prefabbed and ready to go with just a screw driver and some caulk........Ill post more when I can.