As an avid biker, I'm a big fan of safety. Other than helmets, lights are probably the biggest thing a biker can do to improve their safety on the road.
Unfortunately I live in a big mean city and like to keep my light in my bag when my bike is locked up. A problem I've frequently encountered with my light is that it will randomly turn on in my backpack far too easily which drains the battery. Very frustrating.
I was able to solve this problem quite elegantly with Sugru.
Materials 1x - planet Bike rear light 1x - packet of Sugru