In recent days I've been designing the light boxes and researching LEDs for the pieces with colored/clear epoxy. Since my first sculpture with epoxy (below), I have always thought about possibly backlighting the sculptures but was happy to avoid it by pulling them off the wall and using just a little dye. With these new pieces, however, the wood is too thick and the slots too narrow for enough light to get through naturally. As a result, I'm forced to engineer a backlighting system.
Now, after a fair amount of experimenting and research, I now have the knowledge for why this should be avoided. As expected, it isn't very easy to both generate enough light and make it battery powered with a reasonable amount of run time. To make it battery powered, LEDs are really the only solution but they still require a fair amount of electricity. It will definitely take a good amount of experimentation to find the right combination of LEDs, wiring configurations, and batteries. My first few attempts were a total bust. Below is my test wiring with four 5mm, 3.6 volt, 1100mcd (a measure of brightness), 20 milliamp, and 30 degree viewing angle LEDs. When I put it behind a mock-up light box I had virtually no light come through the epoxy.
Luckily, I found this website, Quickar, in researching how to wire LEDs. I ordered some 10 mm lamps from them a couple of days ago because they were said to produce a lot of light and have a 180 degree viewing angle, but when I got a note back saying they were out of them, I called and talked to Mark for about 45 minutes on how to proceed. He was very helpful and suggested a couple of other lamps to experiment with. It turns out that I was lucky the 10 mm LEDs weren't available because the leads on them couldn't be bent or cut and they also generated too much heat. It sounds like the "superflux" LEDs are the way to go. I couldn't find them on the website but he is sending what he thinks would be best.
A few years ago when I first considered doing something like this, I thought lighting technology would be the limiting factor, and maybe it was, but now it is definately battery technology. From a technical standpoint, the best thing to do would be to uses florescent bulbs and tell the buyers to higher an electrician to put an outlet behind the piece -- a possibility when my works is going for many thousands of dollars, but not really realistic now. Instead, I'll have to experiment with a few configurations and hope to get a fair amount of run time out of the batteries.