Here is my light box. I coodged it together in about 2 minutes one day 10 years ago and I've been using it ever since. I like it because I can set it aside when I need the space and use the makings for other things. I can throw it away if I move. It didn't cost anything. It works.
The light bulb is leaning up against a pottery cup to keep it from getting the box too hot and burning the studio down. If you do this, don't be a klutz and walk away with the light burning or you'll be settin' the place on fire. The fixture is one of those wire clamp on jobbies that was on hand for an old display.
I put one sheet of glass on the bottom, a piece of tissue in between to diffuse the bright light and a recycled (broken corner) piece of scrap glass on the top. It works just fine. If you're loaded and have a fancy light box, forget I said anything. If you always wanted one but couldn't afford it, this post was for you.