I'm not very familiar with 3D printing, so I'm not sure about tolerance between moving parts. Anyway there is a fast explanation of my design and how to model it in 3DS Max. It's not a full modeling tutorial, because it would have been too long and complicated, but I'll show you the main phases and I'll attach the 3ds complete model in next step so you can see it in your 3D favorite software.
Step 1: Some sketches
I also made a big mistake in modeling, which I could have avoided if I had looked better at my drawings (yes I know that you're thinking there is not much information in them!).
The project consists in a flat safe-box with a combination lock. It's very flat, about 8 mm thick, and it's arranged with two inner compartments. You can keep inside a lot of folded banknotes or a ring, a necklace, anything fits in a 4 mm drawer.