I do not like to use glue for anything I may need or repair, so I did a quick remix of the original model. You will need 6 M3 x 12 mm screws and assorted nuts.
Use the original strands and small parts.
To unlock the handcuff, insert the key, turn it 90 degres and, with the key still turned, rotate the strand.
2023-04-04 update : added the small parts and strands STL files, from the original model. No change done to them, this is just for downloading everything easily.
2023-08-11 update : clearance around the nuts seems to be too tight. Updloaded new files (tagged V2) with greater clearance. Previous files are in “Tigh clearance” directory.
2023-11-05 update : depending on your use, the teeth of the strands may be a little bit short lived. I have added a Strand-Locks-v2 file with bigger teeth. You must change both the strands and the lock parts. Because the locks are also included in the original files, I have added a new « small parts » file, identical to the original model minus the locks. All those files are in the « Big teeth » directory.
Print either the print_stands-10 and print_small_parts-10 (regular teeth) or the Strands-Locks-v2 (bigger teeth) and (if you are not upgrading an existing print) the print_small_parts-v2 file. If you are upgrading an existing model, only print the Stands-Locks-v2 file.
Assembly instructions :
The handcuffs have a “double lock” mechanism (the small white dots on the photo) :
When the strands are closed, you may push on those two dots with elongated part of the key :
You should hear a small click. The double lock is active. To unlock the handcuffs, you will have to turn the key in one direction (small click) and then in the other direction.
An advice : print several keys ! Nothing is more annoying than a broken or lost key.
The author remixed this model.
Use M3 fasteners and nuts, not glue.