LED Engagement Ring

A ring with built-in LED chip.

First I made 2 identical rings.

if you don't have access to a chuck lathe, you can buy two rings.
Check here for a chuck lathe in your city: http://hackerspaces.org/wiki/lathe

draw a recess for the 5mm LED

for the recess, you can use a dremel and a file.

now, you can stuck it together with glue.

one half is the anode, the other half is the cathode.

solder the LED from inside.

now you need a second, similar ring, with a hi-cap capacitor instead of the LED.

--> if the rings touch each other, the LED is shining