Hello there, I'm going to teach you how to create the classic inception box from Spongebob. The best thing about this is you can effectively use this for anything you wish, be it wood, cardboard boxes, steel, glass(Although this kinda defeats the whole purpose of the inception box...
Materials you will need will actually vary depending on what you are creating the boxes out of, for me, I had a wooden inner box, and a cardboard outer box, I will teach you how to make the one I made.
(As a note, I forgot to take pictures of most of the steps, and the finished product is at a workshop, so I apologize for stock images.)
Wood, you need 6 panels of almost 6x6, so atleast a 6x36 in plank.
Cardboard box larger than 6 inches.
Tools necessary to cut wood.
Step 1: Cut a Hole in the Box.
Going to work backwards here, acquire your box and simply cut a hole where the crease will be on the bottom. Nothing real fancy here. You want it to be fairly tall and wide just incase you ever need to hide babushka.
Step 2: Based Wood
For your second step you are going to need to have a 6 by 6 inch main piece of wood. Then another 2 of them will be 6x6, but the second two will have to be 6 x 6 minus twice the thickness of your wood( Height by length.)
Step 3: Notch Off the Old Block
This step is completely optional, but you may want to do this.
The center piece of wood should be notched that there will be a 1/8th inch ridge surrounded by 1/8th valleys next to each side.
Step 4: NotchStep
For the two main 6x6 pieces, notch the center of the bottom part where it should be 1/4th inches thick. This will allow it to fit snuggly with the center piece.
Step 5: ReNotched
For the two main 6x(6 minus twice the thickness of the wood planks) pieces, notch the center of the bottom part where it should be 1/4th inches thick. This will allow it to fit snuggly with the center piece.
Step 6: Gluttonous Glue
Inside the valleys of all the notches apply a gratuitous amount of glue. And apply pressure when placing the pieces together. Your box should look like this. Of course it shouldn't have these two support beams.
Step 7: You Know the Drill?
On the side part of the wooden box you are going to need to cut open a small hole near the bottom, where you will thread the string through.
Step 8: Boxed Plantation
Firmly grasp the main wooden box, and apply more than enough glue on the bottom and stick it inside the box; since you put the string to one side, that means it will not get stuck.
Step 9: Does It Even Lift?
Now that you have your string out of the way of the glue, you are going to want to cut a hole on the top of the flap you made. Once you are done with that, knot it up and make sure that you can pull the string far enough so you can open it all the way so it becomes 90 degrees.
Step 10: Profit???
Now it isn't really all that secret if you can see your compartment eh? Place the flaps of the cardboard box in so they cover the compartment and cut off the parts you do not need. Glue the flaps to the wooden box and now you have Inception Box.
Ideally you want to have none of the non-wooden box showing, but if you are lazy, just simply cover the part that contains the real magic.
Enjoy you box!