This is a mechanical box with lock inspired by the Chamber of Secrets Door from the Harry Potter movie.

Please note: This model require a lot of assembly operations. The assembly video is 1 hour long and printing time is around 40 hours. Weight of the result is about 320 gramms (ABS). You will have to put a lot of efforts in gluing parts together. The last part (the snakes) is the most challenging which makes things even worse. You might face a situation when you invest a lot of time in printing and gluing and face problem at the very last stage which might be really frustrating.

If I haven't scared you off yet by the previous paragraph then you will be probably fine. I myself have not that much experience in complex assembly and I put a lot of efforts to make this model easy to print and assembly. It is time-consuming though. You might want to print everything at 50% scale to try this model in action. Here is a model optimized for smaller size print: https://www.thingiverse.com/thing:4462717 (it has it's own assembly video which might be useful as well).

This model is pretty large and requires your bed to be at least 180mmx180mm (7"x7").
Printing is pretty easy and almost all the parts does not require support (snake heads and the handle should be supported though).

Almost everything can be printed at .2mm resolution, but the plate_high_resolution.stl file works better at .1mm resolution. Threads are smoother and the snake heads looks better when printed at higher resolutions.

I get small parts together to allow you print them at once, but if you need to reprint one particular object check the all_objects.zip archive. You will find all objects there.

I included OpenScad source files (sources.zip). Feel free to remix the model for your needs.

Here is the video of assembled and painted box: https://www.youtube.com/watch?v=aZzzPDOUkWI
Here is the full assembly video: https://www.youtube.com/watch?v=VsMtNRKIuuo
And the mechanics explained video: https://youtu.be/bPpvi0tVqtY

Comparison of hot glue and ABS juice video: https://youtu.be/CRvIke6Hg9E (because I receive a lot of questions about glue used)

Please let me know if you have any problems with this model, I will try to help.

I used the following models here:
https://www.thingiverse.com/thing:311031 OpenSCAD ISO metric thread library / functions
https://www.thingiverse.com/thing:3833810 PolyGear OpenSCAD Gear Library
https://www.thingiverse.com/thing:2811727 Flexi Snake