What size?

I plan on having 3 soiled plants, how big of a space would I need? Im planning on building something to house the plants in.

maybe 2' x 2'

2' x 2' ? What about height?

it depends on the strain and how big your going to grow them. what kind of lights you got some research to do.

I am planning on growing white widow, and maybe autoflowering ak47? I would like to use cfl lights. I have been doing a lot of research and looking at this site and believe Im ready to get my grow box built. I seen a thread on here https://www.rollitup.org/do-yourself/51417-diy-4oz-minimum-yield-grow.html and I thought that would be perfect. Any thoughts?