GideonTech.com has posted a guide about building a light box

Just about everyone has a digital camera in their possession, or has access to one. Most of these cameras are point and shoot, which offer good pictures for every day affairs. However, what happens if you need something a bit more on the professional side? For example, an image for a presentation or slide show. To get that quality feel without spending a fortune on professional photography equipment, you'll need some quality light settings. We're going to show you how to make yourself a homemade light box to get that look you need.[/quote|
Guide: Building a Light Box