A Focus at Ways to Catch and Store Coins

Base is done—time to tackle accepting and receiving coins. I started this a while ago; it’s been tough. First step: build a container to store coins.

Starting at the Bottom – A Place to Store Coins

Taking coin, using LEGO^®, and then turning that coin into a credit was indeed a very challenging problem. However, before I get too wrapped up with that issue, I first need a place for the coins to go, and a place to store coins.

So, let’s do what I seem to do best, let’s build another box to put into our box!

Photo of Zxibit meme — Yo dawg!
I heard you like boxes!

Boxes on Rails

I tried a couple variations of a sliding rail system for a bin, such as Brick, Modified 1 x 4 with Channel and Plate, Modified 1 x 2 with Door Rail pieces. However, I found these rails a bit too small and fragile to support a large bin that will need to hold a bit of weight in coins. So I ended up landing on utilizing Technic 1×15 Liftarm pieces and placing these on tiles.

Photo showing the bin base sitting on tile from top-down - tiled as it will be a box to store coins — Base of bin with Technic liftarms resting on tile

Photo showing bin base sitting on tile from side — Base of bin with Technic liftarms resting on tile

After deciding on the way that the bin would work, I build the structure holding the bin in place.

Photo showing support built to hold the bin in place — Structure to hold the bin in place

Next, I work to build a door for the bin to sit behind. This door, at least right now, is very simple with hinges to allow the door to swing open. I use Technic brick for the door because I intend to apply some sort of design to the door like I did for the control panel and the base.

Photo showing the hinges of door — HInges placed along the edge of the door

Making the door open and shut easily meant that I couldn’t just use brick. So I try to implement more Technic liftarm pieces to allow for some clearance when the door closes and brick meet. Since the liftarms interlock, I might consider using this to create the locking mechanism for this door.

Photo showing interlocking liftarms at the end of the door — The liftarms interlock

Demonstration photo showing the door closed — Demonstration of the door closed

Now that the basics are figured out, I complete the build of the bin to store coins, and finish off the door.

Photo of the completed bin sitting inside of the cabinet with the door open — Bin sitting inside the cabinet with the door opened

A True Lock, Made of LEGO

Figuring out how to lock the door without a key was a challenge. My first idea—using interlocking liftarms—didn’t work, since a vertical rod would interfere with the internal coin chutes above. So, I switched to a horizontal lever lock design.

So I decide to try a lever lock. A lever lock (also known as a lever tumbler lock) works using a set of flat pieces called levers, which must all be lifted to the correct height by a specially-shaped key in order for the lock to open. If the wrong key is used, the levers won’t line up correctly, and lock stays blocked.

Diagram demonstrating how a lever tumbler lock works - this picture shows the mechanism in the locked position — By Willh26 – Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=47531847

Diagram demonstrating how a lever tumbler lock works - this picture shows the mechanism in the unlocked position — By Willh26 – Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=47531847

Using LEGO Technic parts, I built three levers hanging from an axle. Behind them, a long brick (acting as a rod) holds a pin that gets blocked when the levers hang down. Each lever has a uniquely placed slope that the key pushes up. When all levers are in the correct position, the pin can pass freely through.

Photo showing the created lever tumbler lock — The inside of the lever locking mechanism

I enclosed this mechanism in a box and mounted it on the back of the door. In the locked position, the rod sticks out past the edge of the door, preventing it from opening. I had to flip the rod upside-down so it could slide freely without the studs catching on the levers.

Photo showing the box attached to the back of the door with the upside down "rod" brick resting past the wall where the door opens — The box attached to the door – in locked position – upside down “rod” brick prevents door from opening

Check out the video below for a demonstration.

It’s no Fort Knox, but it works!