I did it, I finally made a light photo-box. After himming & hawing for several weeks, I finally made myself a photo light-box. I looked at it as investment for my Esty shop. I picked up supplies from my local Staples: a box, poster board & packing tape. Once home I gathered all my supplies plus the several sets of instructions I acquired from Etsy's Storque & various blogs. I glanced over all the instructions once then I went to work.
There are some great instructions out there including my sources: http://www.etsy.com/storque/how-to/fortys-foto-tips-2-make-a-light-box-244/ and http://digital-photography-school.com/how-to-make-a-inexpensive-light-tent . I am not going to re-create the wheel here, but share my experience of making the box.
I chose the size box, 12"x18"x12" because I wanted a large field & the ability to change the background & be able to use my 13" Ott Lite table lamp. To allow the flexibility I wanted I made the windows large & completely cut off 2 sides. I made an accident right off the bat & completely cut off the wrong side; that's what happens when you are dyslexic! Besides being the wrong side, it left the box too unstable. I ended up resolving this by making a foam board window for that side & eventually L brackets on the outside. I made a total of 4 windows. The next step was to line the inside with white poster board. You could make the whole box out of white foam board & eliminate this step. I decided not to attach diffusing fabric to the windows for several reasons so I used a curtain draped over the box as a make-shift diffuser. I forgot to purchase fabric & I want to be able to have access through all the windows to change to layout. I think it turned out pretty nifty. Another feature that was necessary was that it had to be compact, I live in a studio apartment & shoot pictures in my very large window. My photo box allows me to take nice pictures & not depend on the weather or time of day & keeps my workspace relatively neat.