I was called upon recently to teach some handcuff escape workshops. In keeping with my tendency to build large demonstration props, I decided to construct a huge, functioning, see-through handcuff.
I designed them in Rhino, cut the layers of acrylic on a laser cutter, and formed the spring from a street sweeper blade using heat and pliers.
The key works by rotating around the keyhole post, lifting the pawl high enough to slip the ratchet.
Don’t have a key, but need to get the cuff off? Shimming works by inserting a thin piece of metal in above the ratchet, closing the ratchet a few clicks tighter, enough to slide the shim under the pawl. At this point, the ratcheted cuff swings free.
Handcuffs typically include a double lock feature which prevents the cuff from tightening once engaged. Shimming doesn’t work on cuffs that have been double locked. I may build a future version of the huge handcuffs that incorporate this feature.