Embedding fasteners or other hardware into 3D prints is a useful technique, but it can bring challenges when applied to large or non-flat objects. The solution? Use a gap-cap.

The gap-cap technique is essentially a 3D printed lid. One pauses a print, inserts hardware, then covers it with a lid before resuming the print. The lid — or gap-cap — does three things. It seals in the part, it fills in empty space left above the component, and it provides a nice flat surface for subsequent layers which makes the whole process much cleaner and more reliable.

This whole technique is a bit reminiscent of the idea of manual supports, except that the inserted piece is intended to be sealed into the print along with the embedded hardware under it.

If you have never inserted anything larger than a nut or small magnet into a 3D print, you may wonder why one needs to bother with a gap-cap at all. The short version is that what works for printing over small bits doesn’t reliably carry over to big, odd-shaped bits.

For one thing, filament generally doesn’t like to stick to embedded hardware. As the size of the inserted object increases, especially if it isn’t flat, it increasingly complicates the printer’s ability to seal it in cleanly. Because most nuts are small, even if the printer gets a little messy it probably doesn’t matter much. But what works for small nuts won’t work for something like an LED strip mounted on its side, as shown here.
Cross-section of a print with an embedded LED strip. The print pauses (A), LED strip is inserted and capped with a gap-cap (B, C), then printing resumes and completes (D).
In cases like these a gap-cap is ideal. By pre-printing a form-fitting cap that covers the inserted hardware, one provides a smooth and flat surface that both seals the component in snugly while providing an ideal surface upon which to resume printing.

If needed, a bit of glue can help ensure a gap-cap doesn’t shift and cause trouble when printing resumes, but we can’t help but recall the pause-and-attach technique of embedding printed elements with the help of a LEGO-like connection. Perhaps a gap-cap designed in such a way would avoid needing any kind of adhesive at all.

hackaday.com/2026/03/27/use-a-…

What did Elliot Williams and Al Williams read on Hackaday last week? Tune in and find out. After a bit of news, [Vik Oliver] chimes in with some deep PLA knowledge. Then the topic changed to pressure advance measurements, SDRs, making super-resolution PCBs with a fiber laser, and more.

Want to 3D print wire strippers? A robot arm? Or just make your own Z-80? Those hacks are in there, too.

For the long articles, we talked about old tech, including the :CueCat and the Iomega Zip Drive. Let us know if you had either one in the comments.

What do you think? Leave us a comment or record something and send it to our mailbag.

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Interesting Hacks of the Week:

• Direct Pressure Advance Measurement For Fast Calibration
  
  • BambuLab eddy sensor
  • Why strain gauge?

  
  

• Building A $50 SDR With 20 MHz Bandwidth
• Using A Fiber Laser To Etch 0.1 Mm PCB Traces
  
  • Laser Etching Printed Circuit Boards
  • Why Are You Still Making PCBs?
  • Supercon 2024: Quick High-Feature Boards With The Circuit Graver

  
  

• Build This Open-Source Graphics Calculator
  
  • Build This Open-Source Graphics Calculator

  
  

• The Most Intricate Of Freeform Digital Clocks
  
  • Bend It Like Bhoite: Circuit Sculptures Shatter The Bounds Of Flatland

  
  

• PicoZ80 Is A Drop-in Replacement For Everyone’s Favorite Zilog CPU
  
  • 770 Zilog Z80 :: Quicker, easier and cheaper to make your own chip!
  • Retrocomputing For $4 With A Z80

  
  

Quick Hacks:

• Elliot’s Picks:
  
  • 3D Printed Wire Stripper Uses PLA Blades
    
    • Hot Wire Strippers

    
    

  • Electric Motorcycles Don’t Have To Be Security Nightmares, But This One Was
  • Demonstrating Gray Codes With Industrial Display
  • 3D Printed Robot Arm Built For Learning Purposes

  
  

• Al’s Picks:
  
  • Arduino Code on My 8051: It’s More Likely Than You Think
  • Analog Video From An 8-Bit Microcontroller
  • A Candle-Powered Game Boy For Post-Apocalyptic Tetris

  
  

Can’t-Miss Articles:

• Retail Fail: The :CueCat Disaster
• From Zip To Nought: The Rise And Fall Of Iomega
  
  • Storage Media Forgotten

  
  

hackaday.com/2026/03/27/hackad…

The people at Signal Snowboards are well known not only for producing quality snowboards, but doing one-off builds out of unusual and perhaps questionable materials just to see what’s possible. From pennies to glass, if it can go on their press (and sometimes even if it can’t) they’ll build a snowboard out of it. At some point, they were challenged to build different types of boards from paper products which resulted in a few interesting final products, but this pushed them to see what else they could build from paper and are now here with an acoustic guitar fashioned almost entirely from cardboard.

For this build, the luthiers are modeling the cardboard guitar on a 50s-era archtop jazz guitar called a Benedetto. The parts can’t all just be CNC machined out of stacks of glued-up cardboard, though. Not only because of the forces involved in their construction, but because the parts are crucial to a guitar’s sound. The top and back are pressed using custom molds to get exactly the right shape needed for a working soundboard, and the sides have another set of molds. The neck, which has the added duty of supporting the tension of the strings, gets special attention here as well. Each piece is filled with resin before being pressed in a manner surprisingly similar to producing snowboards. From there, the parts go to the luthier in Detroit.

At this point all of the parts are treated similarly to how a wood guitar might be built. The parts are trimmed down on a table saw, glued together, and then finished with a router before getting some other finishing treatments. From there the bridge, tuning pegs, pickups, and strings are added before finally getting finished up. The result is impressive, and without looking closely or being told it’s made from cardboard, it’s not obvious that it was the featured material here.

Some of the snowboards that Signal produced during their Every Third Thursday series had similar results as well, and we actually featured a few of their more tech-oriented builds around a decade ago like their LED snowboard and another one which changes music based on how the snowboard is being ridden.

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hackaday.com/2026/03/27/luthie…

Isn’t there some claim events come in threes? After the extremely rare leak of the iOS Coruna exploit chain recently, now we have details from Google on a second significant exploit in the wild, dubbed Darksword.

Like Coruna, Darksword appears to have followed the path of government security contractors, to different government actors, to crypto stealer. It appears to focus on exploits already fixed in modern iOS releases, with most affecting iOS 18 and all patched by iOS 26.3.

Going from almost no public examples of modern iOS exploits to two in as many weeks is wild, so if mobile device security is of interest, be sure to check out the Google write-up.

Another FBI Router Warning

The second too early to be retro – but too important to ignore – repeat security item is a second alert by the FBI cautioning about end-of-life consumer network hardware under active exploitation, with the FBI tracking almost 400,000 device infections so far.

Like the warning two weeks ago, the FBI calls out a handful of consumer routers – but this time they’re devices that may actually still be service in some of our homes (or our less cutting edge friends and family), calling out devices from Netgear, TP-Link, D-Link, and Zyxel:

• Netgear DGN2200v4 and AC1900 R700
• TP-Link Archer C20, TL-WR840N, TL-WR849N, and WR841N
• D-Link DIR-818LW, 850L, and 860L
• Zyxel EMG6726-B10A, VMG1312-B10D, VMG1312-T20B, VMG3925-B10A, VMG3925-B10C, VMG4825-B10A, VMG4927-B50A, VMG8825-T50K

While many of these devices are over ten years old, they still support modern networking – some of them even supporting 802.11ac (also called Wi-Fi 5). Unfortunately, since support has been ended by the manufacturers, publicly disclosed vulnerabilities have not been patched (and now never will be, officially)

Once infected, the routers are enrolled in the AVRecon malware network, which includes the now-typical suite of behavior of remote control, remote VPN access to the internal and external networks, DNS hijacking, and DDoS (distributed denial of service) attacks. This sort of network malware is used by attackers to exploit internal systems like un-patched Windows or IOT devices on the local network, and as a launching point to hide behavior as coming from a certain country or state by using the public Internet connection as a VPN. It’s also often monetized by unscrupulous apps selling cheap VPN service.

The worst type of vulnerability affecting home routers is one which can be triggered remotely from the Internet without user interaction – for instance CVE-2024-12988 which allows arbitrary code execution remotely on Netgear devices, but even vulnerabilities which are only accessible from the local network can be combined with cross-site vulnerabilities or vulnerabilities in other devices to exploit home routers. A malware infection on a Windows system can be leveraged to install additional, permanent malware installs on routers and IOT devices, and malware on a router can be used to redirect the user to install more malware on an internal PC via manipulating the network, or allow direct attack of internal systems via a proxy.

A slight upside is that this batch of vulnerable hardware is often modern enough to run OpenWRT or other replacement firmware. OpenWRT supports thousands of routers and access points – and often forms the basis of the commercial firmware the device was shipped with, before the manufacturer abandoned it. Converting a device to OpenWRT may be intimidating for some, but for anyone with one of the listed devices, the time to try is now! It’s cheaper than buying a new device, and worst case scenario, you’d have to replace that router anyway!

You can use the OpenWRT Table of Hardware to see if there is a version for your device.

Unfortunately, vulnerabilities in home routers don’t offer many lessons: there’s rarely a need to log into them to see if there is a pending update, and almost nothing the typical home user can do except buy a new device when the manufacturer stops supplying security fixes.

Trivy Compromised

The Trivy security scanner suffered a breach themselves, leading to a cascading series of breaches of other tools. Trivy is an automatic vulnerability scanner for finding vulnerabilities is the dependencies of Docker and other container images, package repositories, and language packages in Go, PHP, Python, Node, and many other popular languages. Trivy is often integrated into the CI/CD (continual integration and continual deployment) process of other open and closed source projects and internal company processes.

According to the timeline published by Aqua, in late February 2026 a misconfigured GitHub workflow allowed the theft of authentication tokens for the Trivy project. While the attack was detected and the credentials removed, not all credentials were properly removed, which allowed the attackers to complete the attack on March 19, 2026.

Once compromised, all but one release of the Trivy GitHub actions were replaced with trojaned malicious copies, spreading the compromise to any project which used the Trivy GitHub actions, spreading the malware payload to many projects using the Trivy scanner actions.

GitHub actions are part of GitHub which allows scripts when repository actions like a pull request or merge are performed. Actions can be used to check that a change compiles properly, scan for security issues, generate documentation, or generate release binaries, and typically are allowed to make changes to the repository itself. GitHub workflows can include actions from other repositories via the Action Marketplace. By replacing the Trivy actions, the attackers essentially gained access to every repository using Trivy to scan for vulnerabilities in their own codebases.

The hijacked Trivy actions collected and exfiltrated access tokens for Docker, Google Cloud, Azure, and AWS, Git credentials, SSH keys, and any other secrets from projects using the Trivy actions. With these keys, the controllers of the original malware are able to attack those projects directly, such as the immensely popular LiteLLM Python interface to AI LLM models from multiple companies.

The compromise of LiteLLM also stole credentials to cloud services, SSH, git, Docker, and Kubernetes on any system that ran the trojaned setup scripts, as well as infecting any connected Kubernetes systems found in the configurations.

There are also reports that the malware actors are also infecting NPM node packages with malware which automatically updates itself from a block-chain based control system and steals NPM authentication tokens to inject itself into any NPM packages the victim may have authored.

Supply-chain attacks happening for years with varying levels of success. But the Trivy attack may be the most successful in spreading compromised packages into multiple package repositories. It’s difficult to avoid supply chain attacks, especially when the vulnerability scanner itself is the source of the problem. GitHub has introduced immutable releases – tagged build versions which can not be updated once released, and the immutable release of Trivy was the only version not compromised by the attackers. As more packages shift to immutable versions it may become harder to insert malware into the supply, but we’re nowhere near a tipping point of projects using immutable releases yet.

hackaday.com/2026/03/27/this-w…

Arturo Di Corinto al Festival di Geopolitica, Demarcazioni

Mi ha fatto veramente molto piacere partecipare a Demarcazioni, il primo Festival di Geopolitica appena concluso ad Ascoli Piceno.

Venerdì 20 aprile 2026, nella mia sessione, “I corridoi del potere”, a cui hanno partecipato anche il Ministro Francesco Lollobrigida e il presidente delle marche, Francesco Acquaroli, abbiamo parlato di Sovranità digitale e tecnologica insieme a Giulia Pastorella, Franco Spicciariello e altri relatori moderati dalla collega di Porta a Porta Paola Ferazzoli.

Dal canto mio ho ribadito come oggi la sovranità digitale si declini come autonomia strategica, cioé di come essa comporti l’istituzione e il mantenimento attivo di collaborazioni internazionali dinamiche e mirate, per affrontare proattivamente le minacce alla sovranità stessa (copyright Roberto Baldoni) e che la sovranità non si esercita solo nel controllo sui dati generati dai cittadini dalle imprese e dalla PA contando sull’uso di tecnologie sicure e affidabili.

Sovranità e autonomia si garantiscono anche infatti attraverso il controllo politico e normativo. Perciò non c’è sovranità senza Europa.
Certo, per sfuggire al paradosso della sovranità senza tecnologie, l’Europa deve fare fare di più e sviluppare meglio la sua capacità di innovare e produrre tecnologie utili e affidabili.

L’Italia ci sta provando, attraverso Agenzia per la Cybersicurezza Nazionale e in collaborazione con molti soggetti come l’European Cybersecurity Competence Centre (ECCC).

Perciò grazie agli organizzatori per questo bell’incontro.

DEMARCAZIONI Festival Geopolitica 2026 Ascoli Piceno

dicorinto.it/formazione/sovran…