Enlarge (credit: Kevin Noki)

Have you ever worked on a hobby project where modifying and compiling the source code for a Linux-based emulator was possibly the easiest and most straightforward part of the whole thing?

Kevin Noki really, really wanted a functioning Macintosh Plus, complete with a functioning, auto-ejecting disk drive that it could boot from. The German maker already had a Mac Plus (1Mb) from eBay, but it had both a busted power supply and floppy drive. Rather than carve out the busted Plus' one-of-a-kind internals and slap a Raspberry Pi in there like some DIY slacker, Noki went … a different path.

Noki 3D-printed his own Macintosh , the "Brewintosh." I would like you to consider what you think that last sentence means and then wipe your expectations clean. I have watched the entire 48-minute journey of Noki's Brewintosh, which is both very soothing on some ASMR -adjacent gut level and also low-key maddening for the way it plays down all the individual accomplishments along the way. Any one of the Brewintosh's pieces would be my entire weekend, and my spouse would not enjoy my mood while I was sunk into it.

Enlarge / Penk Chen's Rasti Computer, built with 3D printing, Framework laptop internals, and a deep love for the first laptop that went to space. (credit: Penk Chen )

If I had to figure out what to do with the insides of a Framework 13 laptop I had lying around after today, I might not turn it into a strange but compelling "Slabtop" this time.

No, I think that, having seen Penk Chen's remarkable project to fit Framework parts into a kind of modern restyling of the Grid Compass laptop, I would have to wait until Chen posts detailed build instructions for this project... and until I had a 3D printer... and could gather the custom mechanical keyboard parts. Sure, that's a lot harder, but it's hard to put a price on drawing unnecessary attention to yourself while you chonk away on your faux-used future laptop.

The Rasti Computer, which Chen writes is "derived from the German compound word 'Rasterrahmen' (grid + framework)," has at its core the mainboard, battery, and antennae from the highly modular and repairable first-generation Framework laptop . It takes input from the custom keyboard Chen designed for the chassis, with custom PCB and 3D-printed keycaps and case. It sends images to a 10.4-inch QLED 1600×720 display , and it all fits inside a bevy of 3D-printed pieces with some fairly standard hex-head bolts. Oh, and the hinges from a 2012 13-inch MacBook pro, though that's possibly negotiable.

Enlarge / The 3D-printed hand made via the new method. (credit: ETH Zurich/Thomas Buchner )

Have you ever wondered why robots are unable to walk and move their bodies as fluidly as we do? Some robots can run, jump, or dance with greater efficiency than humans, but their body movements also seem mechanical. The reason for this lies in the bones they lack.

Unlike humans and animals, robots do not have real bones or the flexible tissues that connect them; they have artificial links and joints made of materials like carbon fiber and metal tubes. According to Robert Katzschmann, a professor of robotics at ETH Zurich, these internal structures allow a robot to make movements, grab objects, and maintain different postures. However, since links and joints are made up of hard materials, robot bodies are not as flexible, agile, and soft as human bodies. This is what makes their body movements so stiff.

But they may not need to stay stiff for long. A team of researchers from the Swiss Federal Institute of Technology (ETH) Zurich and US-based startup Inkbit have figured out a way to 3D print the world’s first robotic hand with an internal structure composed of human-like bones, ligaments, and tendons. What makes the hand even more special is that it was printed using an entirely new 3D inkjet deposition method called vision-controlled jetting (VCJ).

Enlarge / Jackson Pollock working in his Long Island studio adjacent to his home in 1949. (credit: Martha Holmes/The LIFE Picture Collection via Getty Image)

If you've ever drizzled honey on a piece of toast, you've noticed how the amber liquid folds and coils in on itself as it hits the toast. The same thing can happen with 3D and 4D printing if the print nozzle is too far from the printing substrate. Harvard scientists have taken a page from the innovative methods of abstract expressionist artist Jackson Pollock —aka the "splatter master"—to exploit the underlying physics rather than try to control it to significantly speed up the process, according to a new paper published in the journal Soft Matter. With the help of machine learning, the authors were able to decorate a cookie with chocolate syrup to demonstrate the viability of their new approach.

As reported previously , Pollock early on employed a "flying filament" or "flying catenary" technique before he perfected his dripping methods. The paint forms various viscous filaments that are thrown against a vertical canvas. The dripping technique involved laying a canvas flat on the floor and then pouring paint on top of it. Sometimes, he poured it directly from a can; sometimes he used a stick, knife, or brush; and sometimes he used a syringe. The artist usually "rhythmically" moved around the canvas as he worked. His style has long fascinated physicists, as evidenced by the controversy surrounding the question of whether or not Pollock's paintings show evidence of fractal patterns.

Back in 2011, Harvard mathematician Lakshminarayanan Mahadevan collaborated with art historian Claude Cernuschi on an article for Physics Today examining Pollock's use of a "coiling instability" in his paintings. The study mathematically describes how a viscous fluid folds onto itself like a coiling rope—just like pouring cold maple syrup on pancakes.

Enlarge / A pendant, espresso cups, and flower planters 3D-printed from used coffee grounds. (credit: Michael Rivera)

Most coffee lovers typically dump the used grounds from their morning cuppa straight into the trash; those more environmentally inclined might use them for composting. But if you're looking for a truly novel application for coffee grounds, consider using them as a sustainable material for 3D printing, as suggested by a recent paper published in DIS '23: Proceedings of the 2023 ACM Designing Interactive Systems Conference.

“You can make a lot of things with coffee grounds,” said co-author Michael Rivera of the University of Colorado, Boulder, and the ATLAS Institute, who specializes in digital fabrication and human-computer interactions. “And when you don’t want it anymore, you can throw it back into a coffee grinder and use the grounds to print again. Our vision is that you could just pick up a few things at a supermarket and online and get going.”

As 3D printers have moved into more widespread use, it has sparked concerns about environmental sustainability, from the high energy consumption to the thermoplastics used as a printing material—most commonly polylactic acid (PLA). PLA waste usually ends up in a landfill where it can take as long as 1,000 years to decompose, per Rivera. While there have been efforts to recycle PLA in the same way plastic (PET) soda bottles are typically recycled, it's an energy-intensive process that can't be done by the average user at home. Adding biomass fillers (bamboo or hemp fiber, oyster shells, and yes, spent coffee grounds) makes recycling even more labor and energy intensive.

Enlarge / Bambu Lab's P1S 3D printer. (credit: Bambu Lab )

Imagine waking in the middle of the night to the sound of your 3D printer, printing away. You know you didn't request a print. In fact, you're sure of it, because your previous project is still on the printer. It sounds like an eerie technological haunting or as if the machines have finally become self-aware. Thankfully, the problem stems from something less creepy but perhaps just as scary: a cloud outage.

As reported by The Verge , on August 15, numerous owners of Bambu Lab 3D printers reported that their device started printing without their consent. It didn't matter if said printing resulted in bent or broken nozzles or other components or if it involved printing a project on top of another . It didn't matter if it was an ungodly time, like 4 in the morning; the printers, which cost anywhere from $599 to $1,449, were printing.

"Started a print @ 11 PM. Time-lapse shows it finish successfully at just before 2 AM. At ~2:30 AM while I slept, the machine started itself again with the last print still on the bed. I see a timestamped time-lapse video that starts at about 2:30 AM," a Reddit user going by u/beehphy complained on the r/BambuLab subreddit.

Enlarge / A 3D-printed Czinger brake node that combines the caliper and upright with 40 percent less mass than a conventional assembly. (credit: Jonathan Gitlin)

Polestar provided a flight from Washington DC to London and back, and two nights in a hotel so we could visit its UK R&D center and attend the Goodwood Festival Of Speed. While we were there, we also spoke to Czinger about 3D printing. Ars does not accept paid editorial content.

Additive manufacturing, or 3D printing as it's more commonly known, is more a tool for rapid prototyping in the auto industry than manufacturing actual parts to be used on actual cars. Well, mostly. An interesting company working in this space is Divergent 3D, which has already been supplying 3D-printed parts like subframes for low-volume cars for several car companies, including Aston Martin and Mercedes-AMG.

Divergent gave rise to another startup called Czinger, which acts as something of a showcase for Divergent's printing tech, using it to build what it says will be the world's fastest production car. We caught up with company founder Kevin Czinger at this year's Goodwood Festival of Speed, where among other things, we discovered Divergent has diversified its client base and is now getting into aviation, 3D printing wings for the drone maker General Atomics.

We took a look at the Czinger 21C at last year's Monterey Car Week —to quickly recap, it's a tandem-seating hybrid supercar with 1,250 hp (932 kW) and a vast amount of aerodynamic downforce that has allowed it to break production car track records at Laguna Seca and the Circuit of the Americas.

Enlarge / The world’s smallest 3D-printed wineglass in silica glass (left) and an optical resonator for fiber optic telecommunication, photographed with scanning electron microscopy. The rim of the glass is smaller than the width of a human hair. (credit: KTH Royal Institute of Technology)

A team of Swedish scientists has developed a novel 3D-printing technique for silica glass that streamlines a complicated energy-intensive process. As a proof of concept, they 3D-printed the world's smallest wineglass (made of actual glass) with a rim smaller than the width of one human hair, as well as an optical resonator for fiber optic telecommunications systems—one of several potential applications for 3D-printed silica glass components. They described their new method in a recent paper in the journal Nature Communications.

“The backbone of the Internet is based on optical fibers made of glass," said co-author Kristinn Gylfason of the KTH Royal Institute of Technology in Stockholm. "In those systems, all kinds of filters and couplers are needed that can now be 3D printed by our technique. This opens many new possibilities.”

Silica glass (i.e., amorphous silicon dioxide) is one material that remains challenging for 3D printing, particularly at the microscale, according to the authors, though several methods seek to address that challenge, including stereolithography, direct ink writing, and digital light processing. Even those have only been able to achieve feature sizes on the order of several tens of micrometers, apart from one 2021 study that reported nanoscale resolution.

Enlarge / Chaotic shapes 3D-printed in bronze represent the first step in the transformation from chaos to manufacturable forms. (credit: F. Bertacchini/P.S. Pantano/E. Bilotta)

A team of Italian scientists has figured out a way of turning the striking, complex twisting shapes of chaos theory into actual jewelry, according to a new paper published in the journal Chaos. These pieces aren't simply inspired by chaos theory; they were directly created from its mathematical principles.

"Seeing the chaotic shapes transformed into real, polished, shiny, physical jewelry was a great pleasure for the whole team. Touching and wearing them was also extremely exciting," said co-author Eleonora Bilotta of the University of Calabria. "We think it is the same joy that a scientist feels when her theory takes form, or when an artist finishes a painting."

The concept of chaos might suggest complete randomness, but to scientists, it denotes systems that are so sensitive to initial conditions that their output appears random, obscuring their underlying internal rules of order: the stock market, rioting crowds, brain waves during an epileptic seizure, or the weather. In a chaotic system, tiny effects are amplified through repetition until the system goes critical. The roots of today's chaos theory rest on a serendipitous discovery in the 1960s by mathematician-turned-meteorologist Edward Lorenz .