OpenSCAD has a lot of fans around these parts — if you’re unaware, it’s essentially a code-based way of designing 3D models. Instead of drawing them up in a CAD program, one writes a script that defines the required geometry. All that is made a little easier with the Belfry OpenSCAD Library (BOSL2).
Designing a part like this is a cinch with BOSL2.
BOSL2 has an extensive library of base shapes, advanced functions for manipulating models, and some really nifty tools for creating attachment points on parts and aligning components with one another. If that sounds handy for designing useful objects, you’re in for even more of a treat when you see their functions for gears, hinges, screws, and more.
There’s even one that covers bottle necks and caps. (Those are all standardized by the way, so it’s never been easier to interface to existing bottles or caps in a project.)
What would it be like to have to design and build a ventilator, suitable for clinical use, in ten days? One that could be built entirely from locally-sourced parts, and kept oxygen waste to a minimum? This is the challenge [John Dingley] and many others faced at the start of COVID-19 pandemic when very little was known for certain.
Back then it was not even known if a vaccine was possible, or how bad it would ultimately get. But it was known that hospitalized patients could not breathe without a ventilator, and based on projections it was possible that the UK as a whole could need as many as 30,000 ventilators within eight weeks. In this worst-case scenario the only option would be to build them locally, and towards that end groups were approached to design and build a ventilator, suitable for clinical use, in just ten days.
A ventilator suitable for use on a patient with an infectious disease has a number of design constraints, even before taking into account the need to use only domestically-sourced parts.
[John] decided to create a documentary called Breathe For Me: Building Ventilators for a COVID Apocalypse, not just to tell the stories of his group and others, but also as a snapshot of what things were like at that time. In short it was challenging, exhausting, occasionally frustrating, but also rewarding to be able to actually deliver a workable solution.
In the end, building tens of thousands of ventilators locally wasn’t required. But [John] felt that the whole experience was a pretty unique situation and a remarkable engineering challenge for him, his team, and many others. He decided to do what he could to document it, a task he approached with a typical hacker spirit: by watching and reading tutorials on everything from conducting and filming interviews to how to use editing software before deciding to just roll up his sleeves and go for it.
We’re very glad he did, and the effort reminds us somewhat of the book IGNITION! which aimed to record a history of technical development that would otherwise have simply disappeared from living memory.
You can watch Breathe for Me just below the page break, and there’s additional information about the film if you’d like to know a bit more. And if you are thinking the name [John Dingley] sounds familiar, that’s probably because we have featured his work — mainly on self-balancing personal electric vehicles — quite a few times in the past.
Disk space is allocated in clusters of a certain size. When a file is written to disk and the file size is smaller than the cluster(s) allocated for it, there is an unused portion of varying size between the end of the file’s data and the end of the allocated clusters. This unused space is the slack space, it’s perfectly normal, and [Zachary Parish] had an idea to write a tool to hide data in it.
The demo uses a usb drive, using the slack space from decoy files to read and write data.
[Zachary]’s tool is in Python and can map available slack space and perform read and write operations on it, treating the disparate locations as a single unified whole in which to store arbitrary files. A little tar and gzip even helps makes things more efficient in the process.
There’s a whole demo implemented on Linux using a usb drive with some decoy files to maximize the slack space, and you can watch it in action in the video embedded below. It’s certainly more practical than hiding data in a podcast!
Note that this is just a demo of the concept. The approach does have potential for handling secret data, but [Zachary] points out that there are — from a serious data forensics point of view– a number of shortcomings in its current form. For example, the way the tool currently structures and handles data makes it quite obvious that something is going on in the slack space.
[Zachary] created this a few years ago and has some ideas about how to address those shortcomings and evolve the tool, so if you have ideas of your own or just want to try it out, the slack_hiderGitHub repository is where you want to go.
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!
Bear with us for a moment for a little background. The Rideau Canal Skateway in Ottawa is the world’s largest natural skating rink, providing nearly 8 km of pristine ice surface during the winter. But maintaining such a large ice surface is a challenge. A regular Zamboni can’t do it; the job is just too big. So the solution is a custom machine called the Froster, conceived by Robert Taillefer and built by Sylvain Fredette.
Froster spans almost twenty meters, and carries almost 4000 L of water. There’s no other practical way to maintain almost 8 km of skating rink.
It’s true that emailed reminders (the agreed-upon — and only — method of contact) going unnoticed to spam was what caused Robert to not take any action until it was too late. We’d all agree that digital assistants in general need to get smarter, and that includes being better at informing the user about automatically-handled things like spam.
But what truly cost Robert Taillefer his patent was having a single point of failure for something very, very important. The lack of any sort of backup method of communication in case of failure or problem meant that this sad experience was, in a way, a disaster just waiting to happen. At least that’s how the Federal Court saw it when he took his complaint to them, and that’s how they continued to see it when he appealed the decision.
If you’ve never heard of the Rideau Canal Skateway or would like to see the Froster in action, check out this short video from the National Capital Commission of Canada, embedded just under the page break.
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.
This technique shared by [Andy Kong] is for 3D printed lenses, but would probably be worth a shot for any resin prints that need to be made nice and clear. The link to his post on X is here, but we’ll summarize below.
It’s entirely possible to print lenses on a resin printer, but some amount of polishing is inevitable because an SLA print still has layer lines, however small. We have seen ways to minimize the work involved to get a usable lens, but when it comes right down to it the printing process creates tiny (but inevitable) surface imperfections that have to be dealt with, one way or another.
3D-printed lenses fresh (and wet) from the printer look clear, but have tiny surface imperfections that must be dealt with.
One technique involves applying a thin layer of liquid resin to the surface of the printed lens, then curing it. This isn’t a complete solution because getting an even distribution of resin over the surface can be a challenge. [Andy] has refined this technique to make it ridiculously simple, and here’s how it works.
After printing the lens, place a drop of liquid resin on the lens surface and stretch some cling wrap over the lens. The cling wrap conforms to the shape and curve of the lens while trapping a super thin layer of liquid resin between the cling wrap film and the lens surface. One then cures the resin while holding the cling film taut. After curing, [Andy] says the film peels right off, leaving an ultra-smooth surface behind. No tedious polishing required!
But what about the flat back of the lens? [Andy] suggests that instead of using cling film (which is better at conforming to a curved surface) simply use a drop of resin in a similar way to bond the flat side of the lens to a smooth piece of glass. Or bond the backs of two lenses together to make a duplex lens. This technique opens quite a few possibilities!
Even if one isn’t 3D printing optical lenses, we suspect this technique might be applicable to making crystal-clear 3D prints with a little less effort than would otherwise be needed.
Keep it in mind, and if you find success (or failure!) let us know on the tips line because we absolutely want to hear about it.
