This model is a 3D printed padlock inspired from a zip tie.
It can be used to lock a bag and protect you from pickpocket in a crowd. It is not very strong but it would take enough time and efforts to break for you to realize something is of.

To lock the mechanism just remove the "key".

To build it you need one of each of the 4 STL files and three M3 8mm screws.

To obtain the best results the main body should be printed in 0.1mm layers with support. Pay attention to thoroughly clean the supports in particular in the locations pointed in the pictures. The other parts can be printed in 0.2 mm layers. The zip part is functional if printed in PLA but ABS gives better results.

You can remove and change the zip part using a phone pin or a needle.

https://www.youtube.com/watch?v=gdSi3PArzHg