Get spooky with a magical halloween coffin that holds a surprise inside. A 2-way mirror and an array of animated lights creates a face-blending illusion, melting your face into a creepy skeleton or other Halloween monster. You can also prop this up and blend two human faces together, creating a very creepy and surreal experience. 

This project requires a little soldering and some software installation, but no coding. It uses an ESP32 Feather board to program and control lights over WiFi, so you can control and change the colors or animations with your smart phone or any web-enabled browser. 

This illusion was inspired by TANZER's Infinity Boxes, and first created for Maker Faire 2024, where we built it inside a Love Tree. It turned out so good that we wanted to recreate it to scare the kids in our neighborhood on Halloween! 

Parts

Additional Materials

• A coffin prop -- I used the Pop-Up Coffin from a Spirit Halloween Store.
• Cardboard
• Black spray paint
• Black Gaffer's tape
• Acrylic Sheet & 2-way mirror film OR a premade 2-way mirror

You'll also need a life-sized skeleton or Halloween monster for the transformation illusion.

The viewer stands on one side of the illusion and the skeleton or monster (or a second viewer) stands on the other side. There is a two-way mirror suspended in the enclosure, spaced evenly in the middle.

There are lights on both sides of the enclosure. When the lights are on the viewer's side, they see a reflection of their own face. When the lights are on the skeleton's side, the viewer can see through the mirror and catch a glimpse of the skeleton.

If the viewer aligns their eyes with the skeleton face, the motion of the lights will appear to blend the two faces together, transforming one into the other and back again. This is spooky with a skeleton transformation -- the flesh appears to melt away into bone and then back again. It's also very effective with a second human on the back side -- the faces melt into each other, creating a visage that's a blend of the two faces.

Feather Setup

Power comes in through the screw terminal and passes through the on/off switch, then splits to go to the Feather (via the JST port) and also to the LEDs. This is a safer way to power a large number of lights, since it doesn't pull all the power the lights require through the delicate electronics in the Feather.

NeoPixel Setup

+5v goes to the red power wire and G goes to the black wire. The DI pin goes to pin 12, though you can use any GPIO pin here. Just be sure to select the correct pin number in WLED setup. 

I've used four 1/2m strips of pixels, with a short "bend point" soldered between the first and last two, and an 8" strand of wire between the middle two. The first two will go on the front of the illusion and the last two will go on the back, so the wire in between should be enough to reach from one side of your enclosure to the other. 

A Word about Connectors

These little locking JST connectors are very handy and they're everywhere in DIY electronics projects. They come soldered to the ends of LED strips and many of us eventually end up with a drawer full of these, salvaged from various projects.

However, there seems to be no industry standard for color-coding. Sometimes you'll find a connector where the red wire is on the left, and sometimes it's on the right. This can be really problematic. When you're knee-deep in a project and trying to keep diagrams straight in your head, it's VERY easy to just roll with whatever color code schema is in front of you. But just because the wire is red on your connector does not mean it's going to neatly line up with the power wires in your project.

NeoPixel Setup

Troubleshooting

If your lights didn't come on, here are a few things to try:

1. Flip your on/off switch. Was it just turned off?
2. Head back to WLED and check your pinout configuration under LED Preferences. Be sure your data wire is connected to pin 12 and that you've told WLED it's on 12.
3. Check your wiring! Be sure you soldered to the IN end of the LED strip. If the arrows on the strip are pointing toward your solder joints, you've got the wrong end -- they should be pointing away.
4. Try re-uploading the WLED software. 
5. Make sure you're on the correct WiFi network - if you're on a different network you won't see the WLED connection.

The two-way mirror is the central piece of this illusion. You can buy two-way mirror online, but it's fairly expensive, especially for a really large piece. Another option is to buy two-way mirror film and an acrylic sheet and make your own. The mirror isn't quite as perfect or clear, but you get a lot more bang for your buck this way.

I got a large piece of acrylic that's 24"x36" so it will fill my coffin edge-to-edge, and I can make a rather large viewing hole. 

Use more tape to secure the microcontroller somewhere out-of-sight, and run the power wire through the hole in the back or through the bottom of the coffin where it can be plugged in easily.

This coffin won't stand up on its own, but it works perfectly tucked into a corner. I got a small kid-sized chair for my skeleton so he sits at kid-face height, more or less, and then leaned the coffin up in front of him in a dark corner.

This illusion works best at night or in a dark room. A lot of ambient light on either side will wreck the illusion. Play around with locations until you find what works.

Open your browser window and navigate to the WLED interface for your project. This will be the name you set  during software setup -- I called mine coffin.local so that's what I type into my browser to connect.

Be sure your device is on the same WiFi network you set up on your microcontroller.

Now it's time to play around and create animations that create the effect you want. I had the most success using a chase animation, slowed down considerably (use the slider at the bottom of the Effects tab to control the speed). The bottom slider will allow you to control the width of the bands. 

What we want here is for the first half of the strip to light up and then go dark, while the second half of the strip turns on. The animation speed and type can really make or break this illusion.

Watch some videos of the illusion "The Infinity Boxes" by TANZER to get some inspiration. Different light settings make this project feel vastly different. WLED gives you the tools to allow your own artistry to come through.

Once you're happy with your animation you can save it as a Preset, and if you tick the box labeled "Apply at Boot" then your animation will start up automatically. when you turn the project on.