Tamper Evident Seal with Container

Hi! I am a mechanical engineering student. For one of my classes, I needed to design a tamper-evident seal, which could easily be broken and reassembled. The purpose of this project was to explore fracture mechanics and the effect of stress concentrators.

This tamper seal resembles a small container on the inside, which could be paused mid-print and have something placed inside of it. The container was designed with 3D printing in mind, as it required no support. The tamper seal is broken upon twisting the top cap off. The inner threads of the bottom piece push upward on the breakable cone to fracture the tabs. Due to geometric constraints, the tamper seal remains intact with the top cap and is unable to be removed without breaking it. This shows the seal has been breached once it is reassembled. 

Aside from the engineering considerations, the container is fun to fidget with and features a locking mechanism at the bottom of the threads. There is a satisfying click each time when closing the cap. 

Please note that the strength required to open the container greatly varies! My partner and I have two different 3D printers. One is a Bambu X1C, the other is an A1. Both were printed with the same settings, but the one printed from the X1C was significantly more difficult to open initially. We believe this could be due to different filaments (I believe the X1C was using PLA+, A1 was regular PLA from Bambu), tolerance of machines, encloser differences, etc.

Here is a link to a video demonstrating this container being opened and closed: