Hi all!

This is my first attempt at writing an Instructable. I hope I'll be able to share a fun idea! It dates back at my childhood, indeed; but in these days I was recalling it to spend some quality time with my kids and I thought that it could become a good starting point to enter this wonderful site.

Getting a chance to submit it to not just one but two separate contest was surely a good motivation, too...

Another small note: english is not my first language, please don't get angry if I'm unclear or if I make some mistake. Any hint or correction is welcome.

Step 1: Materials

Well, as I think is quite immediately clear, this is a Lego project so of course you will need some Lego bricks. It really doesn't matter which kind of pieces you have, as long as they are enough to build what you want.

Of course, bigger is better: gather as many pieces as you can. If you are able to find some transparent brick they will allow you to add some useful "window" to the puzzle.

Second, but not less important, you'll need a small steel ball. Ideal diameter is 6-7 mm (that's around 1/4 inch). You can get it from a broken bearing, or from some exhausted paint marker, or you could simply buy it online...

Probably you could also use one of those balls used as soft air bullets, but I'd prefer to go for a steel one; that's because the knack of this game is that you have to use your hearing, instead of your sight, to try to guess where the ball is inside the maze, and an heavier ball makes a more distinct rattling noise when it rolls over Lego studs.

To check that the ball is OK you can simply see if it can roll freely in a "ditch" between two bricks like the one you can see in the image. If it's able to jump over the studs and is not too large, you're ready to go.

Step 2: Design the Maze!

Well, as long as it's fun to use Tinkercad, let's face it: if you are not in the process of writing an instructable, you might as well skip this step and start directly building the labyrinth... but for completeness, I'd decided to insert these sketches: they are so more clear and immediately understandable than simple photos! Besides, the fact that I am a less-than-decent photographer sure does not help, either.

Let's see how I designed this. First, I put together a base of the proper size. In this example I'm showing you a small, easy maze. It's not intended to be a though challenge, but just a fun toy for my children, that are 6 and 9 years old.

Then, I started building layer after layer of bricks, leaving in each one the corridors in which the balls will run. Care must be taken to connect the corridors vertically as well. As the layers, or floors if you prefer, start stacking three dimensional path will remain between the blocks, and there will be dead ends, pitfalls, turns, all of those fine labyrinth-y kind of things.

To avoid leaving the course of the maze totally invisible, I also put in a bunch of transparent blocks and windows. Actually they help very little in the solution of the puzzle, but they give another thing to watch and to gather interest from the player.

In the unlikely case that someone would like to see original Tinkercad files, here are the links:

Note: for these designs I made use of the lego bricks created by Nic Ashby, so I happily give him credit for his nice work.

Step 3: Build the Maze!

Ok, as I said before, this is the real step. Gather your bricks and start putting them together according to my design, that's pictured layer after layer in the photos of this section, or the one that you prefer. The wonderful thing about Lego, as always, is that you can freely experiment and you can easily take it apart and start again if you are not satisfied with the result.

You just absolutely have to remember to leave at least an entrance and an exit, and to double check that there is at least a path that connects them, no matter how complicated.

If you really want to make it hard, just find a second ball and put it in a secluded path that's not going anywhere: this will add a second noise that will not be easy to distinguish from the "real" ball...

Step 4: Play It!

When the maze is completed, just put the ball in the entrance and start tilting and rotating it, trying to make the ball advance in the path by force of gravity. Even if you built it yourself, still it will be not that easy to judge if you are sending the ball in the right path just by hearing the noise it makes. Of course, if you have kept the design hidden from the players, it will be even more difficult for them!

In the video you can see my daughter solving the puzzle. That's after she had spent several minutes figuring it out and so she's able to let the ball out in a matter of seconds. As a last hints, you could also use a chronograph to time the attempts, and make a tournament with your friends!

Have fun!