With a few items salvaged and picked up in car boot sales you can make an effective PCB exposure box for less than half the price of the cheapest commercial boxes. I have made four of these units (some double sided) yet still use the first one I made nearly ten years ago!
I have decided to update my old battered box with a snazzy new one and thought it would be a good idea to share my experiences.
Step 1: Basic materials
A metal clad tool case (Maplin, B&Q, tool shops - see photos).
Perspex sheet 3mm thick and the size of the inner rim of the lip of your box (see photo later).
M3 Nuts, bolts and washers (20 or so will cover it).
Black card sheet (A3 size, Staples).
2x UV-A tubes - not blacklight tubes, you need to get the right ones (Rapid, CPC, Specialist).
Tube "U" clips to fit the tubes - metal sprung type.
Mains rated switch (Maplin, Rapid, CPC etc...).
Mains flex 3M or so, 3 core 5A (to use whole and stripped into conductors).
Heatshrink tubing slightly larger than the wiring you will use (inner conductors of mains flex).
3A Terminal block or "chocstrip"
Mains strain relief cable gland (Maplin, electrical supplier) to fit your mains cable.
Various short screws, pan head and countersunk self tapping.
2 small blocks of wood 1"x1"
Mirrored card/plastic or tin-foil.
Crimp tool for ring terminal.
Small flatblade screwdriver
Cross blade screwdriver
Long nose pliers.
Knife or scalpel.