a basic mechanical iris, with additional parts so you can use it as a peep hole. Admittedly, it isn't a great peep hole, which is probably why I never released it. Some nice optics would make a big difference.
the “door tube” goes inside your door, with the octopus outside and the iris inside. again, it wasn’t a great peep hole in practice.
I don't remember for sure, but I suspect I started with this https://www.thingiverse.com/thing:773759
The author marked this model as their own original creation.