Step 1: Equipment Needed
2. 5mm LED (~3.0v, mine were 2.5v)
3. 3v watch battery - from dollar store, so $0.33 each
4. wire - I used extra wire I had
5 soldering iron with solder
6. simple on/off switch - the most expensive item
7. electrical tape
8. clear tape
9. box knife
Cost: ~$6.00 (would be less, but I purchased in small numbers)
Step 2: Prepping the Box
Step 3: Soldering and Hole Poking
I have used electrical tape on the battery. I tried to solder directly to the battery, it didn't work and the battery got very hot. I think it's not safe to apply heat directly to a battery. You may have to flip the battery to make sure that you have the battery polarity matched with the LED.
You will then poke holes for the LED and Switch. I used the box knife to make X cuts then used a Phillips screw driver to clean the holed out. On the switch side, you want to be sure not to make the hole too big. The nut on the switch needs something to grab onto.