Here is a short how-to on building a bike flasher with a couple leds, and a 555 timer. I saw how overpriced they were online and decided that it would be easy enough to build one myself.
by DIY Ideas - Tutorials - DIY
by Maddieslifestyle
by Magic Art and Craft
by HappyJewelrySupplies
by 7D Tech
by Richard Morley
by KovaiCraft