One of my hobbies is origami which is the art of folding paper, coming from Japan. Perhaps I will put a link to some pictures of what I have done so far. I will see.
Origami includes folding animals (like fishes, lions...), geometrical shapes using only one sheet of paper, or many sheets which have to be assembled without glue and those are called "modular origami". Many more folding techniques exist.
So why do I talk to you about that? Well because I made a puzzle using subway tickets that I fold like origami. See below:
I made the puzzle using quite a lot amount of tickets.The cube has a side length of about 10 centimeters (3.9 inches). I think this is quite original.
As for the difficulty, it is not overly difficult but still a bit challenging.
This puzzle is not as sturdy as metal (of course) but it's ok if you are not a brute ;-)
I also made other interesting model using subway tickets (see below). The first from the left required more than 3,000 subway tickets (!!) and has a side length of about 30 centimeters!! It took me years to collect all the tickets.This is a fractal and more specifically a Menger sponge. I don't think I will go for a bigger Menger sponge because it would have a side length of about 1 meter, would be very heavy, and would need something like 66,000 tickets.......
Hope you like it