3D Modeling With Paper As An Alternative To 3D Printing

September 13, 2025 by Maya Posch 32 Comments

Manual arrangement of the parts in Pepakura Designer. (Credit: Arvin Podder)

Although these days it would seem that everyone and their pets are running 3D printers to churn out all the models and gadgets that their hearts desire, a more traditional approach to creating physical 3D models is in the form of paper models. These use designs printed on paper sheets that are cut out and assembled using basic glue, but creating these designs is much easier these days, as [Arvin Poddar] demonstrates in a recent article.

The cool part about making these paper models is that you create them from any regular 3D mesh, with any STL or similar file from your favorite 3D printer model site like Printables or Thingiverse being fair game, though [Arvin] notes that reducing mesh faces can be trickier than modelling from scratch. In this case he created the SR-71 model from scratch in Blender, featuring 732 triangles. What the right number of faces is depends on the target paper type and your assembly skills.

Following mesh modelling step is mesh unfolding into a 2D shape, which is where you have a few software options, like the paid-for-but-full-featured Pepakura Designer demonstrated, as well as the ‘Paper Model’ exporter for Blender.

Beyond the software used to create the SR-71 model in the article, the only tools you really need are a color printer, paper, scissor,s and suitable glue. Of course you are always free to use fancier tools than these to print and cut, but the bar here is pretty low for the assembly. Although making functional parts isn’t the goal here, there is a lot to be said for paper models for pure display pieces and to get children interested in 3D modelling.

Running Code On A PAX Credit Card Payment Machine

September 12, 2025 by Maya Posch 7 Comments

The PAX D177 PoS terminal helpfully tells you which tamper points got triggered. (Credit: Lucas Teske)

These days Points of Sale (PoS) usually include a digital payment terminal of some description, some of which are positively small, such as the Mini PoS terminals that PAX sells. Of course, since it has a CPU and a screen it must be hacked to run something else, and maybe discover something fun about the hardware in the process. Thus [Lucas Tuske] set out to do exactly this with a PAX D177 PoS, starting with purchasing three units: one to tear apart, one to bypass tamper protections on and one to keep as intact reference.

As expected, there are a few tamper protections in place, starting with pads that detect when the back cover is removed and a PCB that’s densely covered in fine traces to prevent sneaky drilling. Although tripping the tamper protections does not seem to affect the contents of the Flash, the firmware is signed. Furthermore the secrets like keys that are stored in NVRAM are purged, rendering the device effectively useless to any attacker.

The SoC that forms the brains of the whole operations is the relatively obscure MH1903, which is made by MegaHunt and comes in a dizzying number of variants that are found in applications like these PoS terminals. Fortunately the same SoC is also found on a development board with the AIR105 MCU that turns out to feature the same MH1903 core. These are ARM Cortex-M3 cores, which makes targeting them somewhat easier.

Rather than try to break the secure boot of the existing SoC, [Lucas] opted to replace the SoC package with a brand new one, which was its own adventure. Although one could say that this is cheating, it made getting a PoC of custom code running on one of these devices significantly easier. In a foll0w-up article [Lucas] expects to have Doom running on this device before long.

Analog Optical Computer For Inference And Combinatorial Optimization

September 11, 2025 by Maya Posch 17 Comments

Although computers are overwhelmingly digital today, there’s a good point to be made that analog computers are the more efficient approach for specific applications. The authors behind a recent paper in Nature are arguing that inference – essential for LLMs – can be done significantly more efficiently using an analog optical computer (AOC).

As the authors describe it, the function of this AOC is to perform a fixed-point search using only optical and analog electronic components. The optics handle the matrix-vector multiplications, while the analog components handle the non-linear operations, subtractions and annealing. This is performed in 20 ns cycles until noise has been reduced to an acceptable level, considering the analog nature of the computer. A big advantage here is that no analog-digital conversions are required as with other (digital) hybrid systems.

So far a small-scale AOC has been constructed for tasks like image classification and non-linear regression tasks, with the authors claiming the AOC being over a hundred times more efficient than current GPU-derived vector processors.

Using An MCU’s Own Debug Peripheral To Defeat Bootrom Protection

September 10, 2025 by Maya Posch 2 Comments

The patient hooked up for some reverse-engineering. (Credit: Caralynx, Twitter)

Released in July of 2025, the Tamagotchi Paradise may look somewhat like the late 90s toy that terrorized parents and teachers alike for years, but it’s significantly more complex and powerful hardware-wise. This has led many to dig into its ARM Cortex-M3-powered guts, including [Yukai Li] who recently tripped over a hidden section in the bootrom of the dual-core Sonix SNC73410 MCU that makes up most of the smarts inside this new Tamagotchi toy.

Interestingly, [Yukai] did see that the visible part of the bootrom image calls into the addresses that make up the hidden part right in the reset handler, which suggests that after reset this hidden bootrom section is accessible, just not when trying to read it via e.g. SWD as the hiding occurs before the SWD interface becomes active. This led [Yukai] to look at a way to make this ROM section not hidden by using the Cortex-M3’s standard Flash Patch and Breakpoint (FPB) unit. This approach is covered in the project’s source file.

With this code running, the FPB successfully unset the responsible ROM hide bit in the OSC_CTRL register, allowing the full bootrom to be dumped via SWD and thus defeating this copy protection with relatively little effort.

Heading image: PCB and other components of a torn-down Tamagotchi Paradise. (Credit: Tamagotchi Center)

Bare Metal STM32: The Various Real Time Clock Flavors

September 10, 2025 by Maya Posch 8 Comments

Keeping track of time is essential, even for microcontrollers, which is why a real-time clock (RTC) peripheral is a common feature in MCUs. In the case of the STM32 family there are three varieties of RTC peripherals, with the newest two creatively called ‘RTC2′ and RTC3’, to contrast them from the very basic and barebones RTC that debuted with the STM32F1 series.

Commonly experienced in the ubiquitous and often cloned STM32F103 MCU, this ‘RTC1’ features little more than a basic 32-bit counter alongside an alarm feature and a collection of battery-backed registers that requires you to do all of the heavy lifting of time and date keeping yourself. This is quite a contrast with the two rather similar successor RTC peripherals, which seem to insist on doing everything possible themselves – except offer you that basic counter – including giving you a full-blown calendar and today’s time with consideration for 12/24 hour format, DST and much more.

With such a wide gulf between RTC1 and its successors, this raises the question of how to best approach these from a low-level perspective.

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Bambu Lab’s PLA Tough+ Filament: Mostly A Tough Sell

September 9, 2025 by Maya Posch 21 Comments

Beyond the simple world of basic PLA filaments there is a whole wild world of additives that can change this humble material for better or worse. The most common additives here are primarily to add color, but other additives seek to specifically improve certain properties of PLA. For example Bambu Lab’s new PLA Tough+ filament series that [Dr. Igor Gaspar] over at the My Tech Fun YouTube channel had over for reviewing purposes.

According to Bambu Lab’s claims for the filament, it’s supposed to have ‘up to’ double the layer adhesion strength as their basic PLA, while being much more robust when it comes to flexing and ‘taking a beating’. Yet as [Igor] goes through his battery of tests – comparing PLA Tough+ against the basic PLA – the supposedly tough filament is significantly worse in every count. That sad streak lasts until the impact tests, which is where we see a curious set of results – as shown above – as well as [Igor]’s new set of impact testing toys being put through their paces.

Of note is that although the Tough+ variants tested are consistently less brittle than their basic PLA counterparts, the Silver basic PLA variant makes an unexpectedly impressive showing. This is a good example of how color additives can have very positive impacts on a basic polymer like PLA, as well as a good indication that at least Bambu Lab’s Basic PLA in its Silver variant is basically better than Tough+ filaments. Not only does it not require higher printing temperatures, it also doesn’t produce more smelly VOCs, while being overall more robust.

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A Love Letter To Internet Relay Chat

September 8, 2025 by Maya Posch 60 Comments

Although kids these days tend to hang out on so-called “Social Media”, Internet Relay Chat (IRC) was first, by decades. IRC is a real-time communication technology that allows people to socialize online in both chat rooms and private chat sessions. In a recent video [The Serial Port] channel dedicates a video to IRC and why all of this makes it into such a great piece of technology, not to mention a great part of recent history. As a decentralized communication protocol, anyone can set up an IRC server and connect multiple servers into networks, with the source code for these servers readily available ever since its inception by a student, and IRC clients are correspondingly very easy to write.

Because of the straightforward protocol, IRC will happily work on even a Commodore 64, while also enabling all kinds of special services (‘bots’) to be implemented. Even better, the very personal nature of individual IRC networks and channels on them provides an environment where people can be anonymous and yet know each other, somewhat like hanging out at a local hackerspace or pub, depending on the channel. In these channels, people can share information, help each other with technical questions, or just goof off.

In this time of Discord, WhatsApp, and other Big Corp-regulated proprietary real-time communication services, it’s nice to pop back on IRC and to be reminded, as it’s put in the video, of a time when the Internet was a place to escape to, not escape from. Although IRC isn’t as popular as it was around 2000, it’s still alive and kicking. We think it will be around until the end days.

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