3D printing is known for producing parts with a fairly average finish at best. Even the smoothest resin prints are still fairly plasticky and dull in appearance. However, it’s possible to do much better if you get creative with electroplating. This thermal detonator prop from [HEN3DRIK] shows just how good a 3D print can look with a little post-processing and some chemical help.
[HEN3DRIK] started with a Star Wars thermal detonator model found online, and printed it in resin for the best possible surface finish from the get go. The parts were cleaned after printing and cured, as per usual resin processing techniques. From there, fine steel wool and sandpaper was used to make the print as smooth as possible. A conductive layer of copper paint was then sprayed on with an airbrush, with mating surfaces masked off to avoid ruining the fit.
The part was then dunked in an acidic copper bath while attached to a power source, and gently rotated during the electroplating process. The results were excellent, resulting in near-mirror finish copper-plated parts after polishing. Nickel was then plated on top to get the prop to the proper silver color. The prop was finally then assembled with an Arduino Nano inside to run several LEDs for visual effect.
Clocks are a mainstay of hackers and makers, as they provide a way to explore creative designs while still maintaining a functional aspect to the project. [Brett Oliver] follows this tradition in making a cyclotron clock that uses a perpetual rotating digit concept from a 1900s desk flip calendar.
Each digit of the clock has a rotating chamber that’s big enough to fit a group of tiles inside that have digits printed on either face. The tiles are sized and stacked in such a way that the rotation of the chamber allows the next tile to slide in front of the old one. Specific digits are revealed by rotating the chamber a number of times.
Each of the four digits positions has a 28BYJ-48 stepper motor to rotate the chamber, with each motor being driven by a ULN2003 driver module. The main microcontroller is a ESP32 WROOM, and an I2C compatible DS3231 real time clock (RTC) module keeps time. All of the motors are driven off of an LM2596 module that provides 7 V, while the ESP32 and RTC are powered from a USB connector.
The different modes and the ability to set time is done through a panel that has various buttons and knobs. The whole clock is mounted on a custom wooden base that has cutouts for the panels and cabling. [Brett Oliver] has done a great job of documentation, going into detail about the mechanics and electronics of the build. Design files, including STLs of the various components, are also available for download. Be sure to check out the video after the break.
We’ve featured a flip calendar with a similar operating principle before which clearly shows the inner workings of the mechanism.
Pyramid salt crystals can grow naturally, and typically occur in locations where salt pools are undisturbed under the warmth of the sun. However, it’s possible to grow them on purpose, too. As a bonus, their hollow structure means they dissolve very quickly on the tongue, and can taste “saltier” than typical granular salt.
To grow your own, you’ll need a bag of salt, which is mixed with some water. You’ll want to do so in a glass dish, as the salty solution you’ll be making can ruin metal cookware. The dish can then be heated up on an electric hotplate, which is used to heat the solution to between 60 and 70°C.
A small amount of food-grade potassium alum is also added to the solution to calm the convection currents in the heated solution, allowing the crystals to form gently without sticking and clumping together. As the water boils away, the rectangular-pyramidal crystals grow.
Naturally, you must be careful before eating the results of any home-grown lab experiments. However, [Chase] reports having licked some of the crystals and has confirmed they do indeed taste salty. [Chase] also notes several ways in which the parameters can be changed to grow different types of pyramid crystals, too.
The project works in a relatively simple fashion: essentially, a Raspberry Pi Pico is charged with reading an HC-SR04 ultrasonic rangefinder. It’s all wrapped up in a 3D-printed skull-like housing. When the skeleton detects someone or something close in front, the Pi triggers a small servo hooked up to a 3D-printed gear. This interfaces with a pair of racks which drive the skull’s eyebrows up and down, and opens and shuts its jaw.
Of course, there are some major anatomical problems here. Skulls don’t have eyebrows; that’s just not possible. Eyebrows are hair attached to flesh and muscle; they simply don’t exist in the world of bone. However, it’s fair to say [Kevin]’s taking creative license for the sake of the holiday, and we can all support that.
This is a basic build, and a fun one. It would be an excellent way to learn some basic microcontroller skills, while also serving as a great little Halloween charm to scare guests going back to the fridge for another beverage.
We get a cavalcade of quality holiday hacks every year around this time. This year should be no exception – so get your spooktacular hacks into the tips line, post-haste! Video after the break.
Hedges aren’t just a pretty garden decoration. They’re also a major habitat for many species of insects, birds, and other wildlife. In some areas, a lot of hedge trimming goes during the time that local birds are raising their fledglings, which causes harm at a crucial time. Thus, [Johann Elias Stoetzer] and fellow students were inspired to create Hedge Watcher.
The concept is simple – using thermal vision to spot birds inside a hedge when they may not otherwise be easily visible. Many species blend in with their surroundings in a visual manner, so thermal imaging is a great way to get around this. It can help to avoid destroying nests or otherwise harming birds when trimming back hedges. The idea was sourced from large-scale agricultural operations, which regularly use thermal cameras mounted on drones to look for wildlife before harvesting a field.
However, staring at a thermal camera readout every few seconds while trimming hedges isn’t exactly practical. Instead, the students created an augmented reality (AR) monocular to allow the user to trim hedges at the same time as keeping an eye on the thermal camera feed. Further work involved testing a binocular AR headset, as well as a VR headset. The AR setups proved most useful as they allowed for better situational awareness while working.
It’s a creative solution to protecting the local birdlife, and is to be applauded. There’s plenty of hubris around potential uses for augmented reality, but this is a great example of a real and practical one. And, if you’re keen to experiment with AR yourself, note that it doesn’t have to break the bank either!
Who do you think of when you think of ancient civilizations? Romans? Greeks? Chinese? India? Egyptians? What about the Scythians, the Muisca, Gana, or the Kerma? You might not recognize that second group as readily because they all didn’t have writing systems. The same goes, to a lesser extent, for the Etruscans, the Minoans, or the inhabitants of Easter Island where they wrote, but no one remembers how to read their writing. Even the Egyptians were mysterious until the discovery of the Rosetta stone. We imagine that an author writing in Etruscan didn’t think that no one would be able to read the writing in the future–they probably thought they were recording their thoughts for all eternity. Hubris? Maybe, but what about our documents that are increasingly stored as bits somewhere?
If you aren’t up to speed on [Frank Herbert]’s sci-fi epic, the Fremen are a warrior race that populates the sands of the desert planet Arrakis, which is inhabited by giant sandworms. The worms are attracted to vibrations, and thumpers are supposed to be mechanical devices set into the sand to lure worms. Thumpers are only vaguely described in the text, and have been imagined to varying degrees of success in the filmed versions of the story.
[Attoparsec] decided to take a stab at a working version, with the twist of making it plausible within what’s known about the Fremen in the stories. He settled on a pneumatic drive, which seems like something the Fremen would use. Using compressed CO2 cartridges, he discovered that it’s far easier to make a high-speed pneumatic vibrator than it is to make a piston move slowly up and down. Several iterations were needed to get to a mechanism capable of the more stately movements seen in any of the film versions of the story, and even then the thumping seems a bit fast for our liking. The triggering mechanism was very cool, though, and somewhat unexpected — [Herbert] describes “lighting the candle” to trigger a thumper, which led to the use of a thermal pressure relief valve and a fuse.
The video below goes over the design and build in some detail, as well as demonstrates the thumper in action with a clever cosplay bit. Hats off to [Attoparsec] for this dive down the fandom rabbit hole, maybe a faithful version of the “pain box” will be next up on the project list.