With the zombies, ghouls, and ghosts now safely returned to their crypts until next October, it’s time to unveil this year’s winners for the 2023 Halloween Hackfest.

For this contest, sponsors DigiKey and Arduino challenged the community to come up with their best creations for what’s arguably the most hacker-friendly of holidays. Pretty much everything was fair game, from costumes to decorations. The top three winners will get $150 credit from DigiKey and some treats from Arduino — just don’t try to eat them.

First Prize: Flying Ghost

Halloween offers a rare opportunity to not only take your creations out into the world, but to terrorize passerby without consequence. You’d be hard pressed to find a better example of that spirit, no pun intended, than the Flying Ghost created by [Scott Duckworth].

We’ve seen various RC aircraft get dressed up for the holiday in the past, but this example is a bit different. Rather than build his ghost around a free-flying rotorcraft, [Scott] suspended his haunter from a cable system that was connected to a trio of beefy winches that could be controlled by a central microcontroller using RF24L01+ modules. With a sprinkle of trilateration, the system was able to convert the length of line in each winch into a 3D position over the street. After the sun goes gown, the result is an illuminated ghost that can swoop over the heads of trick-or-treaters in silence with no obvious means of propulsion.

Or at least, that was the idea. Unfortunately, [Scott] ran into a glitch that prevented the central controller from calculating the ghost’s position on Halloween, and there wasn’t enough time to sort it out before the roving bands of sugar bandits showed up. Not all was lost, as the ghost was still hanging menacingly over the street, but it wasn’t able to move around. Naturally, it only took a few minutes to figure out the problem on November 1st. Hey, at least he’ll be ready for 2024.

What was the problem, you ask? He had defined a variable as int16_t when it should have been int32_t — real spooky stuff around these parts.

Second Prize: Fire Dragon

This fire-breathing dragon head from [Science Shack] started its life as a realistic mask from Amazon, but after the addition of some animatronic hardware and a bit of flammable gas, it’s more than just a pretty face.

A lightweight acrylic “skeleton” inside the mask is articulated with three servos, which is enough to provide a reptilian-like head motion without getting too bogged down in the details. A fourth servo is used to depress the nozzle on a can of butane as part of the the 3D printed “flamethrower” in the beast’s mouth. After the gas travels through a small brass tube, it’s lit off with a spark and the dragon is able to belch out an impressive flame. Luckily the mask’s latex construction is relatively heat-resistant, so it doesn’t melt itself when the heat is on.

Third Prize: Haunted Keyboard

When you think of traditional Halloween decorations and props, a mechanical keyboard probably doesn’t make the cut. But what about a haunted keyboard? Well that’s a different story.

This spectral keyboard, created by [Mx. Jack Nelson] is inhabited by the spirit of a particularly terrifying entity: ChatGPT. Once you type in a message, the internal Raspberry Pi Pico forwards it to the large language model (LLM) chatbot so it can produce a suitably spooky response. Once the keyboard receives the results, it “types” them out as if an unseen hand was at work.

The result is something like a futuristic Ouija board; where each question is met with a response that’s just vague enough to make you think there might be some kind of intelligence at work. We still wouldn’t trust it to write any code for us, but as far as Halloween set dressing goes, it seems more than up to the task.

Honorable Mentions

As usual, this contest featured a number of special categories which the judges were asked to consider while placing their votes.

Costume: Electronic Harry Potter Wand

Technically, all you need to dress up as somebody from the Harry Potter universe is some robes and maybe a scarf. But you won’t be much of a witch or a wizard without a wand, where is where this creation from [Mike Kushnerik] comes in.

The wand is powered by an Adafruit RP2040 Prop-Maker Feather microcontroller, which features an onboard LIS3DH three-axis linear accelerometer that’s used to detect when a “spell” is being cast. An RGB LED in the tip of the wand lights up accordingly, and an 18650 cell provides more than enough power to keep the magic going all night.

A 3D printed enclosure helps to sell the wand look while still being rugged enough to handle a night out. We also appreciated the modular nature of the design, which makes future repairs and upgrades easier.

Pumpkin: Animatronic Halloween Pumpkins

According to [Nico], every year his neighborhood holds a pumpkin carving contest. The locals do their best to produce something exciting with the traditional tools of the trade, and then he comes in and slam dunks on their efforts with his  high-tech animatronic singing creations. It truly is the reason for the season.

His creation this year takes the form of a trio of pumpkins, which light up and play audio thanks to a Teensy 3.5 which in turn is controlled by an Android application over a Bluetooth link. While two of the pumpkins look more or less like you’d expect, the third features a large eyeball that uses a pair of servos to look around and blink.

Though we imagine there was a considerable temptation just to 3D print the pumpkins so he’d be able to use them year after year, we appreciate that [Nico] housed his electronics in real gourds.

Kid-Pleaser: Halloween Candy-Pult

What’s better than getting candy? Seeing said candy launched into the air and work its way through a convoluted contraption before you get it, obviously. Or at least, that seems to be the idea behind this entry from [pdxalz]. While admittedly a relatively low-tech project compared to the other entries, it has a fun spirit that made it stand out with the judges.

The original idea was to create a pneumatic “Candy Cannon” which would fire chocolate bars out of a PVC tube barrel. But it tended to destroy the treats in the process, so [pdxalz] changed gears and built a far less aggressive catapult to fling the sweet treats across the porch and into a faux spider web. From there, they fall into a hopper and then work their way down to a waiting bucket.

Hallowed Home: Organ-Playing Skeleton

The components for this project are simple enough: take one broken Hammond organ, combine with a dancing skeleton from the Home Depot, add in a 555 timer, an MP3 playback module, and sprinkle relays liberally. The end result is a otherworldly musical performance with far less complexity than you might expect.

As explained by creator [bryan.lowder], the dancing skeleton from the Home Depot had a way of moving its arms that looked a bit like it was playing the organ once properly positioned. The trick was getting it to do it on command, as the dancing didn’t start until you pressed a “Demo” button attached to its back.

Instead of a microcontroller, he reached for a 555 timer and relay combination that would close the circuit after waiting an appropriate amount of time. The MP3 module, connected to an amplified speaker system, is then kicked in at the appropriate time to complete the scene.

Spooky: Billy RC Tricycle

This last category was an easy one: just build something that’s actually scary. On that account, the judges had no problem identifying the Billy RC Tricycle by [Marcel] as the project they’d least like to run into on a dark October night.

Inspired by previous (but less creepy) RC tricycle projects, the components used to steer and propel this roving hell-hound are expertly hidden. In the dark, you’d swear the puppet mounted to the bike is really pedaling its way towards you. As if that wasn’t bad enough, the custom control board features a DFPlayer module that plays MP3s of unsettling music and manic laughter.

[Marcel] has done a great job documenting the build, and has even provided the files necessary to produce the electronics that allow the tricycle to be remotely operated from a standard PlayStation 3 controller. Under normal circumstances, we’d be happy to see such transparency…but the cowards among us would actually prefer not to see a bunch of Billy clones in 2024.

Only 11 Months to Go…

Halloween is over now, and most people have their eyes on the fast-approaching holiday season. But then, you’re not most people, are you? No, you’re reading Hackaday, and that means you’ve probably started brainstorming what kind of electronic horrors you can put together before Halloween 2024.

If the winners weren’t inspiring enough, make sure to browse through the full list of entries this year. There’s surely something in there that should help get your own macabre machinations off the ground. Just make sure to document your work so you can show it off to us next year.