Here's my DIY bike light. It's based on this, with a few modification.

~700 Lumens of awesomeness with Seoul P4 U-bin LEDs. The lens configuration is L2 5°, 15°, 5°. I only ride on road, so no need for excessive flood.
It can be changed for all 15° or all 5° if need as I'm not using any glass to cover the front. Not worried about getting it wet as the led, lens holder, and wires are all sealed with silicone sealant.

The regulator is Fatman from taskled.com with 50k Log pot for a wide range of adjustable light.

With handlebar mount.

It's a bit dirty as I rode in the rain last night. I didn't get around cleaning it up.

The mounting plate is cut from Planet Bike Beamer 3, with uses the Planet Bike Quick-Cam adjustable bracket (which is quite ubiquitous in Vancouver, and works with Planet Bike Blaze, Beamers, 1200, 5000x, and Super Spot).

I choose this mounting system because I have 2 Planet Bike Beamer 5, and a 5000x (which I will convert to 2 Seoul P4 later on). The interchangeability of the system allows a lot of flexibility of lighting (to see and to be seen).

Helmet mounted.


The helmet mount is from the BLT Ultra Doppler and it allows wide range of angle for the light to point at, with the mounting bracket replaced from a Planet Bike Quick-Cam adjustable.

The battery is connected by a 9v snap connector, with allows me to carry an extra battery pack if I decide to go all night long, or as a backup.

The masking tape will be replaced with electrical tape soon.

Just the mounting plate.