Does anyone know anything about puzzle boxes and how they work?

I’ve been quite interested in 3-d puzzles as of late, and i have a rubix cube, and that is being solved. Then i stumbled across these:

they’re japanese puzzle boxes, and i’m going into woodshop next quarter, so i want to know how to make one. I just don’t understand the concept of how they work…

A quick Google found this site with this link in their FAQ.

Some of those things look absolutely amazing.