how-to

856 Articles

Hardware hacking how-tos

Mockup of a printed copy of the Little OS Book

One Book To Boot Them All

April 2, 2025 by 19 Comments

Somewhere in the universe, there’s a place that lists every x86 operating system from scratch. Not just some bootloaders, or just a kernel stub, but documentation to build a fully functional, interrupt-handling, multitasking-capable OS. [Erik Helin and Adam Renberg] did just that by documenting every step in The Little Book About OS Development.

This is not your typical dry academic textbook. It’s a hands-on, step-by-step guide aimed at hackers, tinkerers, and developers who want to demystify kernel programming. The book walks you through setting up your environment, bootstrapping your OS, handling interrupts, implementing virtual memory, and even tackling system calls and multitasking. It provides just enough detail to get you started but leaves room for exploration – because, let’s be honest, half the fun is in figuring things out yourself.

Completeness and structure are two things that make this book stand out. Other OS dev guides may give you snippets and leave you to assemble the puzzle yourself. This book documents the entire process, including common pitfalls. If you’ve ever been lost in the weeds of segmentation, paging, or serial I/O, this is the map you need. You can read it online or fetch it as a single 75-page long PDF.

Mockup photo source: Matthieu Dixte

Make DIY Conductive, Biodegradable String Right In Your Kitchen

March 28, 2025 by 3 Comments

[ombates] shares a step-by-step method for making a conductive bio-string from scratch, no fancy equipment required. She demonstrates using it to create a decorative top with touch-sensitive parts, controlling animations on an RGB LED pendant. To top it off, it’s even biodegradable!

The string is an alginate-based bioplastic that can be made at home and is shaped in a way that it can be woven or knitted. Alginate comes primarily from seaweed, and it gels in the presence of calcium ions. [ombates] relies on this to make a goopy mixture that, once extruded into a calcium chloride bath, forms a thin rubbery length that can be dried into the strings you see here. By adding carbon to the mixture, the resulting string is darkened in color and also conductive.

There’s no details on what the actual resistance of a segment of this string can be expected to measure, but while it might not be suitable to use as wiring it is certainly conductive enough to act as a touch sensor in a manner similar to the banana synthesizer. It would similarly be compatible with a Makey Makey (the original and incredibly popular hardware board for turning household objects into touch sensors.)

What you see here is [ombates]’ wearable demonstration, using the white (non-conductive) string interwoven with dark (conductive) portions connected to an Adafruit Circuit Playground board mounted as an LED pendant, with the conductive parts used as touch sensors.

Alginate is sometimes used to make dental molds and while alginate molds lose their dimensional accuracy as they dry out, for this string that’s not really a concern. If you give it a try, visit our tip line to let us know how it turned out!

How To Use LLMs For Programming Tasks

March 11, 2025 by 59 Comments

[Simon Willison] has put together a list of how, exactly, one goes about using a large language models (LLM) to help write code. If you have wondered just what the workflow and techniques look like, give it a read. It’s full of examples, strategies, and useful tips for effectively using AI assistants like ChatGPT, Claude, and others to do useful programming work.

It’s a very practical document, with [Simon] emphasizing realistic expectations and the importance of managing context (both in terms of giving the LLM direction, as well as the model’s context in terms of being mindful of how much the LLM can fit in its ‘head’ at once.) It is useful to picture an LLM as a capable and obedient but over-confident programming intern or assistant, albeit one that never gets bored or annoyed. Useful work can be done, but testing is crucial and human oversight simply cannot be automated away.

Even if one has no interest in using LLMs to help in writing production code, there’s still a lot of useful work they can do to speed up the process of software development in general, especially when learning. They can help research options, interactively explore unfamiliar codebases, or prototype ideas quickly. [Simon] provides useful strategies for all these, and more.

If you have wondered how exactly glorified chatbots can meaningfully help with software development, [Simon]’s writeup hopefully gives you some new ideas. And if this is is all leaving you curious about how exactly LLMs work, in the time it takes to enjoy a warm coffee you can learn how they do what they do, no math required.

[Quinn Dunki] Makes A Screw Shortener Fit For Kings

February 16, 2025 by 48 Comments

It’s common problem when you’re building anything with screws: this one is too long, this one is too short. While she can’t teach you how to fix the latter, [Quinn Dunki] has made herself an absolutely deluxe screw shortening jig. And while that’s cool and all, the real value here is the journey; watching over [Quinn]’s shoulders while she’s in the machine shop is always illuminating.

First off, she starts with her old jig, which frankly makes us want one. It’s a short piece of aluminum angle stock with threaded holes in it. You thread the screw in as far as you want, and use the edge as a cutting guide. Very nice!

But aluminum threads wear out quickly so it works if you’re shortening dozens of screws, but gets wonky when you need to cut hundreds. The new jig is made out of steel, and has a slit that clamps the threads in place so she doesn’t have to hold the tiny screws with her other hand while sawing.

This video is, on the surface, about making an improved tool out of steel. But it’s the tips along the way that make it worth your watch. For instance “deburr early and often” is a recurring leitmotif here: it keeps the extra bits that form along any cut from messing up edge finding or vise registration. And yeah, she deburrs after every operation.

There are mistakes, and lessons learned along the way. We’re not going to spoil it all. But in the end, it’s a sweet tool that we’ve never seen before.

If you haven’t read [Quinn]’s series on machine tools that she wrote for us, it’s a treasure trove of machining wisdom.

Continue reading “[Quinn Dunki] Makes A Screw Shortener Fit For Kings” →

Make Custom Shirts With A 3D Print, Just Add Bleach

February 10, 2025 by 38 Comments

Bleach is a handy way to mark fabrics, and it turns out that combining bleach with a 3D-printed design is an awfully quick-working and effective way to stamp a design onto a shirt.

Plain PLA stamp with bleach gives a slightly distressed look to this design.

While conceptually simple, the details make the difference. Spraying bleach onto the stamp surface helps get even coverage, and having the stamp facing “up” and lowering the shirt onto the stamp helps prevent bleach from running where it shouldn’t. Prompt application of hot air with a heat gun (followed by neutralizing or flushing any remaining bleach by rinsing in plenty of cold water) helps keep the edges of the design clean and sharp.

We wondered if combining techniques with some of the tips on how to 3D print ink stamps would yield even better results. For instance, we notice the PLA stamp (used to make the design in the images here) produces sharp lines with a slightly “eroded” look overall. This is very much like the result of inking with a stamp printed in PLA. With a stamp printed in flex filament, inking gives much more even results, and we suspect the same might be true for bleach.

Of course, don’t forget that it’s possible to 3D print directly onto fabric if you want your designs to be a little more controlled (and possibly in multiple colors). Or, try silkscreening. Who knew there were so many options for putting designs onto shirts? If you try it out and learn anything, let us know by sending in a tip!

Continue reading “Make Custom Shirts With A 3D Print, Just Add Bleach” →

Solid Tips For Designing Assistive Technology (Or Anything Else, Really)

February 6, 2025 by 8 Comments

Do you make things, and have you got almost ten minutes to spare? If not, make the time because this video by [PrintLab] is chock-full of healthy and practical design tips. It’s about effective design of Assistive Technology, but the design concepts extend far beyond that scope.

It’s about making things that are not just functional tools, but objects that are genuinely desirable and meaningful to people’s lives. There are going to be constraints, but constraints aren’t limits on creativity. Heck, some of the best devices are fantastic in their simplicity, like this magnetic spoon.

It’s not just about functionality. Colors, textures, and style are all meaningful — and have never been more accessible.

One item that is particularly applicable in our community is something our own [Jenny List] has talked about: don’t fall into the engineer-saviour trap. The video makes a similar point in that it’s easy and natural to jump straight into your own ideas, but it’s critical not to make assumptions. What works in one’s head may not work in someone’s actual life. The best solutions start with a solid and thorough understanding of an issue, the constraints, and details of people’s real lives.

Another very good point is that designs don’t spring fully-formed from a workbench, so prototype freely using cardboard, models, 3D printing, or whatever else makes sense to you. Don’t be stingy with your prototyping! As long as you’re learning something each time, you’re on the right path.

And when a design is complete? It has the potential to help others, so share it! But sharing and opening your design isn’t just about putting the files online. It’s also about making it as easy as possible for others to recreate, integrate, or modify your work for their own needs. This may mean making clear documentation or guides, optimizing your design for ease of editing, and sharing the rationale behind your design choices to help others can build on your work effectively.

The whole video is excellent, and it’s embedded here just under the page break. Does designing assistive technology appeal to you? If so, then you may be interested in the Make:able challenge which challenges people to design and make a 3D printable product (or prototype) that improves the day-to-day life of someone with a disability, or the elderly. Be bold! You might truly help someone’s life.

Continue reading “Solid Tips For Designing Assistive Technology (Or Anything Else, Really)” →

Wearables queen [Becky Stern] with a microcontroller and a speaker. And a skull!

Wearable Tech Tips Directly From The Queen

February 2, 2025 by 8 Comments

What’s the only thing cooler than building something electronic? That’s right — wearing it proudly for all to see.

But maybe you’re not into wearables. Maybe it’s because you’re afraid of sewing, or simply scared that you won’t be able to launder that blinkenshirt you’ve always wanted to make. Well, the undisputed queen of wearables — [Becky Stern] — has a bunch of beginner tips for making DIY wearables. She’s created dozens and dozens of wearable projects and matching tutorials over the years and has graced these pages many times.

As [Becky] points out, once you have your idea sorted, the next thing you need is the tools to get the skills to do the parts you don’t know how to do yet. Even if that’s almost all of it, then this is the guide for you. Importantly, [Becky] reminds us that we should only bite off what we can chew, and that ready-made modules and such are perfectly fine.

There are some tips here that may surprise you. For instance, [Becky] recommends against conductive thread for beginners who already know how to sew by hand, largely because of power delivery and other issues. She also is somewhat anti-lithium battery pouch, preferring instead to use a couple of AAs or a USB battery bank for the renewability aspect.

Be sure to check out the video after the break, which has these tips and more.
Continue reading “Wearable Tech Tips Directly From The Queen” →