I enjoy going on Thingiverse at times, and one time I found this really intriguing two-part print (try googling "thingiverse tube maze puzzle") that looks like a cylinder when put together. However, with enough turning, pulling and pushing, the two pieces fall apart to reveal a secret compartment inside! The design is just beautiful. However, owing to the fact that I'm a 13 year old with no steady income, I've left this idea in the back of my head to 3D print this "someday" for quite a while.

But I changed my mind.
Enter this project. A simple, minimalistic puzzle, ideal for kids, built on the base of 2 cardboard tubes. Perfect for holding your final rations of toilet paper! This project is easily built in an hour or two.

Supplies

To make this, you'll need:
- A cardboard tube ("But zakbobdop, toilet paper is hard to get right now!" "Just cut off a bit from a gift wrapper tube like I did", I'll reply).
- Cardboard
- Glue (I used a mix of paper gel and hot glue)
- Wooden skewers

Step 1: Lock

Cut out a piece of skewer, and glue it to the inside of the larger cardboard tube. It should end up looking like this. This piece will lock the larger tube to the smaller tube.

Step 2: Walls

The wall part of the puzzle uses a technique to make cardboard flexible. To do this, cut out a long, thin strip of cardboard, and peel off the back paper. This makes the strip bendy. Make multiple of these.

Step 3: Walls (Part 2)

Take a strip. Wrap it around the base of the smaller tube. This extension should make the small tube now fit snugly into the larger tube. If it doesn't, wrap some extra cardboard around it to make it thicker.

Step 4: Walls 3, the Epic Finale to the Walls Trilogy

Above the first wall, make a second one. However, this one will have a "hole" in it. This will let the skewer slot through it, and is what makes the puzzle openable (I hope that's a word). Keep making these holed walls all the way up the tube, and you should have something like this.

Step 5: End Caps

Cut out 2 cardboard circles. They should be about the size of the large cardboard tube's opening, and can sit on it without falling in. These circles should be glued in specific places:
1: At the bottom of the smaller tube, under the wall without a hole, and
2: At the "Top" of the larger tube (the side opposite of the end with the skewer).

Try slipping the smaller tube into the larger one! Twisting it right will make the 2 pieces fit into each other nicely, like in my fourth picture.

Step 6: Frustrating Mod

To make this puzzle unbelievably hard, (Seriously, I thought I was never gonna pull it apart again!) just take bits of straw and glue them between the walls to make extra walls.

Step 7: Bonus: Stand

I built the stand with some leftover bendy cardboard I had, a pair of cut skewers, and a large rectangle.
Glue the 2 skewers to the stand, and glue the bendy cardboard on top. The curved shape is perfect for holding the puzzle!