Just to document an old hack I made several years ago…
I will not give detailed build instructions for this DIY Bike Light System unless a request is made to me. Suffice it to say that I have used this lighting system for 6 years on all terrain and never lost a flashlight. Yes, those are PVC sprinkler pipes, snap-tees, 4-way, Tees, and hose clamps. No glue up. The 4-way is secured with small screws. All snap-tees are compression fit with a strip of aluminum tape inserted into the joint. The aluminum tape provides a tight fit which still allows easy rotational adjustment. A PVC-to-metal joint is better than PVC-to-PVC one for this application. When riding at night I will typically point one flashlight towards the water bottle on my down tube. This further illuminates me to motorists, forming moving shadows of my legs against the ground and to cars behind me. This light also helps me see the bottle cages when I am done taking a drink. Other LED flashlights are directed for short range (5-15 feet) and others are adjusted to longer range (15+ feet). I use rechargeable AAA batteries for the LED flashlights.
Lights are easily removed and inserted into the snap-tee. Many times I will grab a light from my mountain bike hanging in the garage for another job just because they are so handy.
Not shown in the images is the bright red flasher on the rear seat pack. It is a store bought LED light with a variety of flashing modes.