I don't know why I love things that bring headache. I have to admit that solving a puzzle is complicated, but making one is much more complicated. Well, I made one. Pardon my bad woodworking. I do need a workbench and jigs and more practices :D
I made this 11 cm x 11 cm x 11 cm Twist-Push-Pull to unlock the cube. Inside we have narrow space for keeping small things such as TF cards or some paper. Actually we can make more spaces for container. My calculation is we have 2 cm x 2 cm x 2 cm on every corner of the inner cube. But to keep the cube simple, then I have two 10 cm x 10 cm x 0.5 cm free spaces in the cube.
Let's take a look at the mechanical inside...
Here we have two cubes and two pieces of wood serving as the lock. The outer cube I use 45 degrees angle cuts to provide 6 identical surfaces. That's what puzzles are supposed to do right? You will never know which side is which. Well, it depends on your crafting :D
Then we put two pieces of wood as the lock. The sticks have to be pulled out of the lock to open the cube.
The inner cube is made to hold the mechanical sticks so that they won't get off their tracks. This cube can be shrunk to get more container spaces, but you need to do some math so that the mechanical pieces inside do not get stuck. Here I made simple cube, with no angle cuts. 9.5 cm x 9 cm x 9 cm where the 0.5 cm of the 9.5 cm is actually the space for lock piece but I use it to glue the inner cube to the outer. We need one surface of the outer to hold the inner cube.