Three feet is kinda short, leaving a scrog as probably your best alternative for a box that size. But, you're probably going to have to get some really good fluorescent lights - like some T-5's - to pull it off. You should figure 9" for the pots + 6 for the plant = 15", leaving you 21" for the light and buds - so, it'll be tight, but it's doable.

You need to study up on scrog's before you try one, but your impression is essentially correct. You install a screen in your box about 6" above the top of your pots. (This distance can be greater, but in your case you want it about as close as you can get it.) The plant grows under the screen, the buds grow up through the screen.

Good luck with your project! :thumbsup:

PC :smokin: