You guys all know about the double-locking mechanism on police-issue cuffs, of course. Now, thanks to a brilliant idea from levis501sub, you can make handcuffs impossible for the prisoner to get out of even if he has a handcuff key! The trick, as described on this guy’s Tumble page, is to disable the double locking mechanism using zip ties or padlocks. For the padlock version, he carefully enlarged the double-locking hole with a metal drill, and after the double lock is engaged he adds the padlocks. VERY clever!

See much more detailed information — and lots more handcuff pictures and ideas — at levis501sub’s Tumblr page, located here.