Ever since I have been getting into alternative processes it's been clear that I needed a UV source of my own. It seems there are a few different options, from cheap and cheerful to quite expensive:
You can read an exhaustive review of the options here at the Unblinking Eye.
I decided that I didn't want the hassle of making my own unit and so searched around for something reasonable and robust. Fortunately, I found the Arista UV Lightsources available from Freestyle. It comes in two sizes 20x24 for $699 and 30x36 for $1,999. They are pizza oven style boxes made of aluminum with a front flap that lifts up to accept the contact printing frame. They use relatively little energy and with such a large heavy metal box, heat is well dissipated even after the unit has been on for several hours. My unit, the smaller of the two, appears to power up nice and quickly. The unit comes with a metal sheet that covers the bottom but once you put the box on a flat surface I don't think its really worth putting in place. I doubt this will cause any problems but I wouldn't place the unit on a nice wooden table! There is a 3/4" lip of metal around the bottom on all sides but the front. This could get in the way with larger 16x20 contact frames.
The internal dimensions of the box are 25" wide, 20 1/4" deep and 2 1/2" tall. You could actually use a frame that was 3 1/2" thick if it were 20x23" maximum external dimensions. My 23 3/4 by 19 3/4" frame (external dimension of the 16x20") fits but the pizza oven flap doesn't quite close completely. That's fine. I'm not planning on leaving my fingers around the opening to get a tan. I've had nothing but even exposures with both cyanotype and platinum prints.
Alternative UV printing boxes that are available tend to be made of wood and are a little pricier. I'm sure they work since they are sold by Bostick & Sullivan but I suspect that the Arista units are better value for money and appear to be more robust in design.