*The links are in the pinned comment.

This is my Assassin’s Creed inspired hidden blade 3D model (Syndicate edition) equipped with a unique mechanism, every single detail of that is 3D printable, except for a nylon cord. There’s no need for screws, nuts, springs, magnets, ball bearings or even rubber bands. All you need is 100g of standard PETG filament and a piece of nylon cord (0.6-0.8mm thick).

An assembly approach has been inspired by the handguns assembly process, which can be done in a matter of seconds by using no tools. By combining several functions in each detail of the mechanism I managed to reduce the overall number of them down to 11.