I built this light back in the early to mid 2000s when the LED flashlights were very expensive and generally not available. As can be seen, it runs off a single AAA cell, and lights a single LED. I used point to point wiring, then I put clear silicone seal over the circuit to hold it in place. The white LEDs were expensoive back then; $4.00 at Radio Shack or $2.00 if bought online. But the most expensive part of the light was probably the box, which cost about $4.00. The switch cost a few dollars, too. Nowadays I have several Fenix LD01 single AAA cell keychain lights, and they perform so much better than this light that I can only say that it served its purpose back then, but has now become a relic.