I started this project last year when I was searching for a small keychain sized light. I wanted something that is small ( N sized or AAA at the most) and durable but reasonably bright. There wasn't much choice and most mods have exposed reflector and LED which is unacceptable for me.
My initial plan is to built a N sized light with optional AAA body so that I can use them with MJ's microconverter pill or Li-ion DD pill. Half way thru the building process, DJpark came out with the regulated POP Li-ion converter and recently, AW started supplying "N-sized" Li-ion cell. So I built another pill based on POP converter and a N cell body.
Here are some pics of the light:
The light is machined from solid titanium rod. It have lens and bezel o-rings for water resistance.
The converter is epoxied onto a can style aluminium heat sink that is fully threaded for better heat tranfer to the body. It has three brightness level: min, intermediate which is user selectable and a max which is about 350 to 400mA.
The heatsink has a centering "step" bored out so that the LED is perfectly centered.
Some pics of the reflector. The reflectors are designed with a "step" which rest on the heatsink directly instead of pressing on the LED. Thus it act as a heatsink transfering heat to the body effectively as can be seen in the following pics. The step also prevent the LED from being dislogded due to over-tightening.
The reflector is custom built from solid aluminium and has an ion-assisted vacuum deposited aluminium surface that is AR coated. The reflectivity is tested to average about 95% throughout the visible spectrum.