An infinity mirror is an optical illusion that makes a single row of lights look like countless rows of lights, receding into the void forever. It's created by placing a one-way mirror over a second mirror with lights in-between. The lights turn the upper mirror transparent from the outside. Inside, the two mirrored surfaces reflect each other in ever decreasing images. The lights appear to be marching in perspective towards a vanishing point, which gives them the feeling of depth. 

This guide will show you how to build an infinity mirror box lid and light it two different ways:

• a Mini Box that uses press-on Circuit Sticker LEDs
• an Animated Box that uses a strip of NeoPixels controlled by an Adafruit Gemma M0 programmed in beginner-friendly MakeCode.

Both versions can be used to store treasures after the candy is gone and are kid-friendly. The Animated Box uses AAA batteries (rather than LiPo) and a Gemma M0 microcontroller that's inexpensive enough to build in permanently.

Try one or both!

Parts List -- Mini Box Version

Parts List -- Animated Version

Suggested Materials List -- Both Versions

If you don't have any of the items below, you can probably substitute from crafts materials you have on hand.

For either box:

• heart-shaped candy box with thin flat top:
  
  • Mini Box -- about 4 inches wide, holding three pieces of chocolate
  • Animated Box -- about 7 inches wide, holding eight pieces of chocolate
• black cardstock or poster board
• one-way mirror window film (such as this) -- sold in large rolls, but you only need two pieces about the size of your box
• glue stick
• clear tape
• scrap cardboard, cardstock, or paper

For the Animated Box:

• mini zip ties
• clear removable adhesive mini-squares (such as these) to make it easier to attach and detach the microcontroller and battery pack
• shiny red cardboard (such as this) to extend the lid

First, you need to prepare the box lid for the Infinity Mirror. Then go to the page for your version to see how to add the electronics.

For this step you only need the lid and the heart-shaped paper liner. Set aside the bottom of the box with the candy in a safe place (away from pets and chocolate fiends).

Make the Inner Mirror

Make the One-Way Outer Mirror

For the outer mirror, you will cut an opening in the lid and cover it with another piece of window film.

Cut and Attach the Outer Mirror Window Film

Next, go to the section that tells you how to add the electronics for your version!

For the Mini Box, you'll be making a parallel circuit with Chibitronics Circuit Stickers, conductive copper tape, and a 3-volt coin battery. The press-on LEDs make this project a snap! I chose to use seven red LEDs, but you can mix and match as you please (up to the limits of the battery).

Prepare the Box

You need to make an opening at the point of the heart to bring the circuit to the outside. If there's tape holding it together, you may be able to unpeel it and use it to hold the battery. If you can't, just slit the point open.

Prepare the Copper Tape

Unroll enough copper tape to fit around the entire inside of the box, plus about 3 inches. Cut the tape down the middle to make two thinner strips.

You will attach these to the inside of the box to make a circuit that carries electricity from the battery to the LEDs.

Press the battery against the outside of the box, so that the positive side is touching the other copper tape. The LEDs should light up! If not, check that all the components are making a good connection to the circuit.

When everything's working, use clear tape to hold the battery in place. Cut a thin strip of cardstock and slide it underneath the battery when you want to turn the lights off.

Finish the Lid

Turn the LEDs on and flip the lid over to see the infinity mirror in action! If the image is distorted, make sure the window film and the inner mirror are flat and as smooth as possible.

The lid should still fit over the candy in the bottom of the box -- although it will sit a little higher than before you squeezed an infinite number of lights into it.

The Animated Box is a little more complicated than the Mini Box, but the added wow factor when the lights sparkle and flash are worth it.

It uses a NeoPixel strip, which contains 30 individually-addressable LEDs that can change color and turn on and off, one by one. The strip also has alligator clip connectors, which means you can take all the components apart and reuse them in other projects later if you choose.

The following pages show you how to prepare the box, assemble the electronics, and program them in MakeCode.

The NeoPixel Strip comes in a protective plastic sheathing. When you curve it around to fit inside the heart, it makes a handy ledge to rest the inner mirror on. However -- fun fact! -- glue won't stick to the silicone it is made out of.

Instead, to keep the NeoPixel strip in place, you will use mini zip-ties to connect it to itself, and to attach strips of cardstock which you can then glue to the inside of the box.

Connect the NeoPixel Strip to the Gemma M0 Board

Before you glue your NeoPixel strip in place, connect it to the microcontroller board so you can test out your code as you write it.

Connect the Battery Holder

The battery holder can plug right into the board using the JST connector. Leave it turned off until you're ready to attach the whole thing to the candy box. The Gemma can run off the computer while you're programming it.

Now go to the next page to find out how to program your board and lights in MakeCode!

It's simple to program an animated infinity mirror on the Gemma M0 in Microsoft MakeCode! Just open and edit the sample code below and add to or change the light display as you wish. Or, create your own program using the strip code blocks, found in the LIGHT category. You can preview it in the simulator before you download it to your Gemma. There's more information about using MakeCode on the Gemma M0 guide.

To download the file to the board, connect the Gemma M0 to your computer with the USB cable. Press the reset button and it will go into bootloader mode. That means it's ready to receive code.

Click download on the MakeCode page and save the file. It will have a .uf2 extension.

Then find the drive on your computer labeled GEMMABOOT. Drag and drop (or copy and paste) the program into Gemma! You'll know the code was downloaded when the onboard pixel changes to violet.

While the Gemma is still connected to the computer, check how the MakeCode runs on the actual NeoPixel strip so you can make any adjustments.

Next, you'll attach the lights and the Gemma and finish the box!

Optional: To make your box even fancier, use a Circuit Playground Express instead of a Gemma and add sensors and music to your infinity mirror! If you're new to using MakeCode with the CPX, check out the Adafruit MakeCode Guide.

It's time to glue the NeoPixel strip to the lid, and the rest of the electronics to the inner mirror.

Finish Attaching the Neopixel Strip

Attach the Gemma M0 and the Battery Holder to the Inner Mirror

Unlike the Mini Box, the electronics for the Animated Box fills almost the entire lid. So you'll need to build a connector that covers the electronics nicely and gives the lid enough extra height to fit over the candy. I used shiny red cardboard that matched the box.

Build the Lid Connector

Last Touches