Regular followers of this blog or of my flickr account perhaps noticed an enormous improvment in the quality of my macro photos about a year ago; at the time I put together a primitive light tent using foamcore and tissue paper. Although the photographic results of this project were all I could hope for, the tent itself was extremely fragile, awkward to set up, and likely to collapse while shooting. So I took what I learned from my first effort and built an improved tent with a PVC-pipe frame and a bedsheet light diffuser.
I used one length of 3/4 inch schedule 40 pipe per edge of the cube, but left out the bottom front edge for more flexibility in placing sheets of background material; this adds up to 11 segments of pipe in total. Due to laziness and ownership of a compact hatchback I bought this pipe from Home Depot in the form of 11 pre-cut 24 inch lengths. I only had to trim a bit from two of the edges due to the elbow fixtures I used at the two bottom-front corners. All other joints are 3/4" elbows with 1/2" threaded side outlets, simply because this is what Home Depot had at the time. Elbows with 3/4 inch slip-fit side outlets would have been better if available, since I also had to buy 3/4" to 1/2" male threaded reducers to put on the ends of the pipe segments. I left all the joints unglued; it's certainly sturdy enough without gluing and this permits flexibility later: you could replace some of the edges with longer pipe and convert the tent into a much longer or deeper one, for example.
I covered this frame in a white, full-size “tailored bedsheet”, which is servicable if a bit small. For the example shots below I equipped the tent with a sheet of white posterboard propped up and allowed to fall into a curve for that seamless-background-look we're all going for. Other colors would work well too, of course.
More important than the tent itself, however, are the light sources. I'm using four CFL bulbs here, one per side and two above. These fluorescents promise light output equivalent to 100 watt incandescent bulbs and color temperature of 5000 K, which is fairly close to what you can expect from daylight, and much better than ~3200 K tungsten lamps; more importantly, all the bulbs are the same type, so (when shooting in RAW mode especially) you can simply adjust the white balance afterwards to match 5000 K or whatever the color temperature of your light sources is. I'm using two Ikea “Tertial” desk lamps ($8.99 as of June 2013!) on the sides of the tent, and an open bulb with another bulb in a clamp light above.
Results of this setup are pretty satisfying. The photos below have not been retouched other than being adjusted for white balance and maybe brightness or contrast during the import from RAW.