Companies like Wicked Lasers will sell you a Blu-ray diode laser. But this DIY keychain looks flat-out deadly in this photo, like a mini one-shot pistol of the future...that can fire for a whole hour before recharging.
One modder bought a brass keychain from Lowe's, then squeezed a Blu-ray diode inside along with a 200mW lithium ion battery inside. (The photo here is technically of his 6x build of the laser, which actually burns out in about half an hour but operates at 268mW.) No matter how many lasers we see (hopefully not beamed directly into our eyes), we just don't get sick of em. Actually, the ones that shoot right into your eyes are pretty great, too. [Hack n Mod via Hackaday]