A reader asks:

 In the interest of saving money, what about making a light box with a conventional housing for fluorescent tubes and a standard plastic screen?

Answer:

We strongly recommend against doing this unless you are a lighting engineer. The result would be uncalibrated light, very possibly with a significant ultraviolet radiation that could pose a hazard. Unfortunately, we have received horror stories from well-intentioned folks who built a box and suffered corneal and eyelid burns. It is not worth the risk. A good commercial light box, which can be had for less than $300, has been professionally calibrated and clinically tested. The cost is not that much greater than assembling components on the fly. Furthermore, with a doctor’s prescription for use in treating depression, there is now a fair chance that insurance will reimburse part or all of the expense.