Christmas Ornament Has Hidden Compartment, Clever Design

December 22, 2025 by 2 Comments

If you need something clever for a gift, consider this two-part 3D-printed Christmas ornament that has a small secret compartment. But there’s a catch: the print is a challenging one. So make sure your printer is up to the task before you begin (or just mash PRINT and find out).

Want a challenging print that’s also useful? This two-piece ornament has a small gift area inside, and prints without supports.

This design is from [Angus] of [Maker’s Muse] and it’s not just eye-catching, but meticulously designed specifically for 3D printing. In fact, [Angus]’s video (embedded under the page break) is a great round-up of thoughtful design for manufacture (DFM) issues when it comes to filament-based 3D printing.

The ornament prints without supports, which is interesting right off the bat because rounded surfaces (like fillets, or a spherical surface) facing the build plate — even when slightly truncated to provide a flat bottom — are basically very sharp overhangs. That’s a feature that doesn’t generally end up with a good surface finish. [Angus] has a clever solution, and replaces a small section with a flat incline. One can’t tell anything is off by looking at the end result, but it makes all the difference when printing.

There are all kinds of little insights into the specific challenges 3D printing brings, and [Angus] does a fantastic job of highlighting them as he explains his design and addresses the challenges he faced. One spot in particular is the flat area underneath the hang hole. This triangular area is an unsupported bridge, and because of its particular shape, it is trickier to print than normal bridges. The workable solution consists of countersinking a smaller triangle within, but [Angus] is interested in improving this area further and is eager to hear ideas on how to do so. We wonder if he’s tried an approach we covered to get better bridges.

Want to print your own? 3D files are available direct from [Angus]’s site in a pay-what-you-like format. If your 3D printer is up to it, you should be able to make a few before Christmas. But if you’d prefer to set your sights on next year with something that uses power and hardware, this tiny marble machine ornament should raise some eyebrows.

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A grey and blue coreXY 3D printer is shown, with a small camera in place of its hotend. On the print bed is a ChArUco pattern, a grid of square tiles containing alternating black fill and printed patterns.

Calibrating A Printer With Computer Vision And Precise Timing

December 22, 2025 by 12 Comments

[Dennis] of [Made by Dennis] has been building a Voron 0 for fun and education, and since this apparently wasn’t enough of a challenge, decided to add a number of scratch-built improvements and modifications along the way. In his latest video on the journey, he rigorously calibrated the printer’s motion system, including translation distances, the perpendicularity of the axes, and the bed’s position. The goal was to get better than 100-micrometer precision over a 100 mm range, and reaching this required detours into computer vision, clock synchronization, and linear algebra.

To correct for non-perpendicular or distorted axes, [Dennis] calculated a position correction matrix using a camera mounted to the toolhead and a ChArUco board on the print bed. Image recognition software can easily detect the corners of the ChArUco board tiles and identify their positions, and if the camera’s focal length is known, some simple trigonometry gives the camera’s position. By taking pictures at many different points, [Dennis] could calculate a correction matrix which maps the printhead’s reported position to its actual position.

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Ask Hackaday: What Goes Into A Legible Font, And Why Does It Matter?

December 22, 2025 by 43 Comments

Two patent front pages, on the left American with a serif font, on the right British with a sans serif font.
American and British patents, for comparison.

There’s an interesting cultural observation to be made as a writer based in Europe, that we like our sans-serif fonts, while our American friends seem to prefer a font with a serif. It’s something that was particularly noticeable in the days of print advertising, and it becomes very obvious when looking at government documents.

We’ve brought together two 1980s patents from the respective sources to illustrate this, the American RSA encryption patent, and the British drive circuitry patent for the Sinclair flat screen CRT. The American one uses Times New Roman, while the British one uses a sans-serif font which we’re guessing may be Arial. The odd thing is in both cases they exude formality and authority to their respective audiences, but Americans see the sans-serif font as less formal and Europeans see the serif version as old-fashioned. If you thought Brits and Americans were divided by a common language, evidently it runs much deeper than that. Continue reading “Ask Hackaday: What Goes Into A Legible Font, And Why Does It Matter?” →

The Music Of The Sea

December 22, 2025 by 6 Comments

For how crucial whales have been for humanity, from their harvest for meat and oil to their future use of saving the world from a space probe, humans knew very little about them until surprisingly recently. Most people, even in Herman Melville’s time, considered whales to be fish, and it wasn’t until humans went looking for submarines in the mid-1900s that we started to understand the complexities of their songs. And you don’t have to be a submarine pilot to listen now, either; all you need is something like these homemade hydraphones.

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Internet-Connected Consoles Are Retro Now, And That Means Problems

December 22, 2025 by 24 Comments

A long time ago, there was a big difference between PC and console gaming. The former often came with headaches. You’d fight with drivers, struggle with crashes, and grow ever more frustrated dealing with CD piracy checks and endless patches and updates. Meanwhile, consoles offered the exact opposite experience—just slam in a cartridge, and go!

That beautiful feature fell away when consoles joined the Internet. Suddenly there were servers to sign in to and updates to download and a whole bunch of hoops to jump through before you even got to play a game. Now, those early generations of Internet-connected consoles are becoming retro, and that’s introduced a whole new set of problems now the infrastructure is dying or dead. Boot up and play? You must be joking!

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How To Build Good Contact Mics

December 22, 2025 by 10 Comments

We’re most familiar with sound as vibrations that travel through the atmosphere around us. However, sound can also travel through objects, too! If you want to pick it up, you’d do well to start with a contact mic. Thankfully, [The Sound of Machines] has a great primer on how to build one yourself. Check out the video below.

The key to the contact mic is the piezo disc. It’s an element that leverages the piezoelectric effect, converting physical vibration directly into an electrical signal. You can get them in various sizes; smaller ones fit into tight spaces, while larger ones perform better across a wider frequency range.

[The Sound of Machines] explains how to take these simple piezo discs and solder them up with connectors and shielded wire to make them into practical microphones you can use in the field. The video goes down to the bare basics, so even if you’re totally new to electronics, you should be able to follow along. It also covers how to switch up the design to use two piezo discs to deliver a balanced signal over an XLR connector, which can significantly reduce noise.

There’s even a quick exploration of creative techniques, such as building contact mics with things like bendable arms or suction cups to make them easier to mount wherever you need them. A follow-up explores the benefits of active amplification. The demos in the video are great, too. We hear the sound of contact mics immersed in boiling water, pressed up against cracking spaghetti, and even dunked in a pool. It’s all top stuff.

These contact mics are great for all kinds of stuff, from recording foley sounds to building reverb machines out of trash cans and lamps.

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Lichtenberg Lightning In A Bottle, Thanks To The Magic Of Particle Accelerators

December 22, 2025 by 14 Comments

You’ve probably seen Lichtenberg figures before, those lightning-like traces left by high-voltage discharge. The safe way to create them is using an electron beam to embed charge inside an acrylic block, and then shake them loose with a short, sharp tap. The usual technique makes for a great, flat splay of “lightning” that looks great in a rectangular prism or cube on your desk. [Electron Impressions] was getting bored with that, though, and wanted to do something unique — they wanted to capture lightning in a bottle, with a cylindrical-shaped Lichtenberg figure.

They’re still using the kill-you-in-milliseconds linear accelerator that makes for such lovely flat figures, but they need to rotate the cylinder to uniformly deposit charge around its axis. That sounds easy, but remember this is a high-energy electron beam that’s not going to play nice with any electrical components that are put through to drive the spinning.

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