The idea behind this pillbox is that you can only take a single pillbox out because the mechanism won't let you take another one out unless you the last one in. For more details about the project, you can check this link:
https://community.element14.com/technologies/3d-printing/b/blog/posts/stacked-medication-box
And for videos of how it actually works, you can check out these (I suggest you turn on the sound!):
And here is a video of how it looks like from the other side:
The author marked this model as their own original creation.