So you forgot to buy flowers for your partner and it's too late to run out now. But you have a workbench. You are a life hacker, after all. So you probably have duct tape and LEDS and batteries? Then what are you waiting for?
The folks at MAKE put these clever roses together using nothing but the aforementioned items, along with some scotch tape, conductive cloth tape, and a magnet to use as a switch. Hit up the post at MAKE for the full instructions. Oh, and don't actually put these flowers in water.