If you're into photography, or you just want nice clean shots of things you plan to sell, a lightbox is a great investment. You could spend a lot of money on one or cobble one together from scraps. Or you can build this really solid, evenly lit version from a cardboard box, LEDs, batteries and elbow grease.
Instructables user faziefazie put this one together using a simple cardboard box covered in white A4 paper (which he taped down to be as seamless as possible, but admits roll paper would be better), some cheap LEDs, and a custom-built controller to handle all of the lights and power them from a single 9V battery. The whole thing uses affordable electronic components, and the final product folds up nicely.
You will need a soldering iron and some electronics equipment to get everything working -- faziefazie essentially wired all of the LEDs to a central perfboard so he could hit one switch and turn them all on or off. The LEDs even fit into the sides of the lightbox so the object you're photographing is bathed in nice, even light. Hit the link below to see the whole step-by-step, including the parts required and how he did it. Check the comments too -- there are some great lighting suggestions there to consider if you want to try it yourself.
DIY Portable Mini Photo Studio [Instructables]