well, there is nothing new about using solarium lamps for photopositive coated pcbs and I wanted to do the same. So I bought me a used face tanner even with built-in time switch. In the tests it turned out that the steps of the time switch (one minute) were too coarse for my application as the lamp is very strong.
So I hacked it and put in a ATmega328P and a salvaged 16x2 LCD display. The lamp is switched with a solid state relay. What I like on this hack is that it's all just plain standard: power supply, ATmega controller, LCD display and libraries. Even the display fits perfectly into the original case with a small modification. Now I can adjust exposition time in steps of one second. And if I need additional functions it will be easy to add them.
If interested look here: