Deltarune’s Tenna Brought To Life

June 3, 2026 by Bryan Cockfield 1 Comment

For those who have never played the hit video games Undertale and Deltarune, the games are partially known for their interesting characters, many of which have eerie, surreal, and expressive designs. One of the more memorable characters from Deltarune is Tenna, a game show host of sorts whose distinguishing feature is an old television as a head, as well as a colorful suit. As a result he’s been the subject of a number of recreations by various cosplayers and makers like [BigRig Creates].

This version of the character was actually inspired by a previous build by [BunnyBii] which used an iPad as the interactive screen/face. Inside the television, though, the actual human found this to be front heavy and limiting in the ways that it could be used interactively, especially since the only way to see the outside world in this version was with a small endoscope and screen. [BigRig Creates]’s version builds on this idea but swaps out the iPad for a Raspberry Pi, allowing for much more customization, and uses a pair of Xreal glasses instead of a screen for the view of the outside world from in the television.

To get the whole costume together, the head is 3D printed with all of the electronics inside, and a game controller integrated into a handheld microphone controls the animations shown on the screen. A vibrant, custom-tailored suit with white gloves rounds out the ensemble, along with a pair of 3D-printed shoe covers since actual yellow shoes were a bit pricy. There were some interesting problems to solve along the way, specifically with regards to power management for all the electronics, but in the end it all seems to have come together quite well. [BigRig Creates] is no stranger to builds with unusual displays, though; one of our favorites was the world’s largest Nintendo 3DS.

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Adorable ASCII Aquarium Lives On Your Desk

May 24, 2026 by Donald Papp 26 Comments

[Kert Gartner]’s ASCII Aquarium turns a cheap yellow display (CYD) into a tiny simulated aquarium, complete with ASCII sea creatures each with their own behaviors. There’s all kinds of options and even timekeeping functionality, so the miniature water world can also pull its weight as a desk clock.

The fish and other animal movements are not a series of canned animations; each creature has its own behaviors and responses to things like feeding, which is accomplished by tapping on the screen. A hidden menu offers a wide range of configuration and display options, and there’s even an option to export screen contents as bitmaps.

Add a 3D-printed enclosure and the whole thing looks like a pretty nice weekend project. There’s even a display flip mode, just in case you have a spare 50 mm beamsplitter kicking around.

It’s a very clever use of a CYD that shows how good color and graphics can look when one designs with the hardware’s capabilities (and limitations) in mind.

The CYD is an ESP32-based development board with integrated touchscreen display, and is known for its affordable price and wide availability. This one would look great next to a CYD electric jellyfish.

Reservoir Sampling, Or How To Sample Sets Of Unknown Size

July 2, 2025 by Donald Papp 2 Comments

Selecting a random sample from a set is simple. But what about selecting a fair random sample from a set of unknown or indeterminate size? That’s where reservoir sampling comes in, and [Sam Rose] has a beautifully-illustrated, interactive guide to how reservoir sampling works. As far as methods go, it’s as elegant as it is simple, and particularly suited to fairly sampling dynamic datasets like sipping from a firehose of log events.

While reservoir sampling is simple in principle it’s not entirely intuitive to everyone. That’s what makes [Sam]’s interactive essay so helpful; he first articulates the problem before presenting the solution in a way that makes it almost self-evident.

[Sam] uses an imaginary deck of cards to illustrate the problem. If one is being dealt cards one at a time from a deck of unknown size (there could be ten cards, or a million), how can one choose a single card in a way that gives each an equal chance of having been selected? Without collecting them all first?

In a nutshell, the solution is to make a decision every time a new card arrives: hold onto the current card, or replace it with the new one. Each new card is given a 1/n chance of becoming held, where n is the number of cards we’ve seen so far. That’s all it takes. No matter when the dealer stops dealing, each card that has been seen will have had an equal chance of ending up the one selected.

There are a few variations which [Sam] also covers, and practical ways of applying it to log collection, so check it out for yourself.

If [Sam]’s knack for illustrating concepts in an interactive way is your jam, we have one more to point out. Our own Al Williams wrote a piece on Turing machines; the original “universal machine” being a theoretical device with a read/write head and infinite paper tape. A wonderful companion to that article is [Sam]’s piece illustrating exactly how such a Turing machines would work in an interactive way.

Hackaday Links: January 12, 2025

January 12, 2025 by Dan Maloney 5 Comments

The big news story of the week of course has been the wildfires in California, which as of Saturday have burned over 30,000 acres, destroyed 12,000 structures, caused 150,000 people to evacuate, and killed eleven people. Actually, calling them wildfires underplays the situation a bit because there are places where they’ve clearly become firestorms, burning intensely enough to create their own winds, consuming everything in their path in a horrific positive feedback loop. We’ve even seen fire tornados caught on video. We’ve got quite a few connections to the affected area, both personally and professionally, not least of which are all our Supplyframe colleagues in Pasadena, who are under immediate threat from the Eaton fire. We don’t know many details yet, but we’ve heard that some have lost homes. We’ve also got friends at the Jet Propulsion Labs, which closed a few days ago to all but emergency personnel. The fire doesn’t seem to have made it down the mountain yet, but it’s very close as of Saturday noon.

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DIY 3D Hand Controller Using A Webcam And Scripting

October 25, 2024 by Heidi Ulrich 3 Comments

Are you ready to elevate your interactive possibilities without breaking the bank? If so, explore [Caio Bassetti]’s tutorial on creating a full 3D hand controller using only a webcam, MediaPipe Hands, and Three.js. This hack lets you transform a 2D screen into a fully interactive 3D scene—all with your hand movements. If you’re passionate about low-cost, accessible tech, try this yourself – not much else is needed but a webcam and a browser!

The magic of the project lies in using MediaPipe Hands to track key points on your hand, such as the middle finger and wrist, to calculate depth and positioning. Using clever Three.js tricks, the elements can be controlled on a 3D axis. This setup creates a responsive virtual controller, interpreting hand gestures for intuitive movement in the 3D space. The hack also implements a closed-fist gesture to grab and drag objects and detects collisions to add interactivity. It’s a simple, practical build and it performs reliably in most browsers.

For more on this innovation or other exciting DIY hand-tracking projects, browse our archive on gesture control projects, or check out the full article on Codrops. With tools such as MediaPipe and Three.js, turning ideas into reality gets more accessible than ever.

A Non-Musical Use Case For 8-Track

August 28, 2024 by Bryan Cockfield 23 Comments

There was a time in the not-too-distant past when magnetic tape was the primary way of listening to and recording audio. Most of us are familiar with the cassette tape, a four-track system that plays first one side of the tape, then the other. There was the eight-track tape as well which did not have quite as much popularity or longevity but did have a few interesting features that [Serial Hobbyism] took advantage of to make an interactive game.

The defining feature of the eight-track system, beyond the obvious eight tracks on the tape, is that the tape runs in a continuous loop, never needing to be stopped or flipped over. Instead, four buttons select pairs of the eight tracks, moving a head immediately to make the switch on-the-fly. [Serial Hobbyism]’s game plays a trivia-style audio recording and asks the player to answer questions by pushing one of the four “program” buttons to switch tracks. If the correct track is selected, the recorded audio congratulates the player and then continues on with the game. Likewise, if an incorrect track is selected, the recording notes that and the game continues.

Another interesting feature of this game is that it can be played without modifying an eight-track player, as the selectable tracks are a core function of this technology. They can be used in a similar way as cassette tapes to store computer data and a data recorder similar to the eight-track system was used on the Voyager space probes, although these only bear a passing resemblance.

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Tool Generates Interactive PCB Diagrams From KiCAD

August 3, 2021 by Donald Papp 21 Comments

Nearly everyone likes nice pinout diagrams, but the more pins and functions are involved, the more cluttered and less useful the diagram becomes. To address this, [Jan Mrázek] created Pinion, a tool to help generate interactive diagrams from KiCad design files.

The result is an interactive diagram that can be viewed in any web browser. Hovering over a pin or pad highlights those signals with a callout for the name, and clicking makes it stay highlighted for easier reference. Further information can be as detailed or as brief as needed.

Interestingly, Pinion isn’t a web service that relies on any kind of backend. The diagrams are static HTML and JavaScript only, easily included in web pages or embedded in GitHub documentation.

If you think Pinion looks a bit familiar, you’re probably remembering that we covered [Jan]’s much earlier PcbDraw tool, which turned KiCad board files into SVG renderings but had no ability to add labels or interactivity. Pinion is an evolution of that earlier idea, and its diagrams are able to act as both documentation and interactive reference, with no reliance on any kind of external service.

Interested? Pinion has a full tutorial and demo and a growing library of parts, so check it out.