[Arnov] has created a really clean wearable design with great build instructions, so anyone who wants to make their own should have an easy time. Prefer to put your own spin on it, or feel inspired by the wrist-mounted enclosure? He’s thoughtfully provided the CAD files as well.
Inside the PIP-WATCH is a neat piece of hardware, the Lilygo T-Display-S3 Long. It’s an ESP32-based board with a wide, touch-enabled, color 180 x 640 display attached. That makes it a perfect fit for a project like this, at least in theory. In practice, [Arnov] found the documentation extremely lacking which made the hardware difficult to use, but he provides code and instructions so there’s no need to go through the same hassles he did.
3D prints destined for presentation need smooth surfaces, and that usually means sanding. [Uncle Jessy] came across an idea he decided to try out for himself: spraying Bondo spot putty onto a 3D print. Bondo spot putty comes from a tube, cures quickly, and sands smoothly. It’s commonly used to hide defects and give 3D prints a great finish. Could spraying liquified Bondo putty onto a 3D print save time, or act as a cheat code for hiding layer lines? [Uncle Jessy] decided to find out.
Gaps and larger flaws still need to be filled by hand, but spray application seems to be a big time saver if nothing else.
The first step is to turn the distinctive red putty into something that can be sprayed through a cheap, ten dollar airbrush. That part was as easy as squeezing putty into a cup and mixing in acetone in that-looks-about-right proportions. A little test spray showed everything working as expected, so [Uncle Jessy] used an iron man mask (smooth surfaces on the outside, textured inside) for a trial run.
Spraying the liquified Bondo putty looks about as easy as spraying paint. The distinctive red makes it easy to see coverage, and it cures very rapidly. It’s super easy to quickly give an object an even coating — even in textured and uneven spots — which is an advantage all on its own. To get a truly smooth surface one still needs to do some sanding, but the application itself looks super easy.
Is it worth doing? [Uncle Jessy] says it depends. First of all, aerosolizing Bondo requires attention to be paid to safety. There’s also a fair bit of setup involved (and a bit of mess) so it might not be worth the hassle for small pieces, but for larger objects it seems like a huge time saver. It certainly seems to cover layer lines nicely, but one is still left with a Bondo-coated object in the end that might require additional sanding, so it’s not necessarily a cheat code for a finished product.
If you think the procedure might be useful, check out the video (embedded below) for a walkthrough. Just remember to do it in a well-ventilated area and wear appropriate PPE.
Yes, the cameras are embedded inside the animatronic eyes.That was a lot easier than expected; rather than the redesign he was afraid of [Will] was able to route the camera cable through his existing animatronic mechanism, and only needed to hollow out the eyeball. The tiny camera’s aperture sits nigh-undetectable within the pupil.
On the software side, face tracking is provided by MediaPipe. It’s currently running on a laptop, but the plan is to embed a Raspberry Pi inside the robot at a later date. MediaPipe tracks any visible face and calculates the X and Y offset to direct the servos. With a dead zone at the center of the image and a little smoothing, the eye motion becomes uncannily natural. [Will] doesn’t say how he’s got it set up to handle more than one face; likely it will just stick with the first object identified.
Eyes aren’t much by themselves, so [Will] goes further by creating a little robot. The adorable head sits on a 3D-printed tapered roller bearing atop a very simple body. Another printed mechanism allows for pivot, and both axes are servo-controlled, bringing the total number of motors up to six. Tracking prefers eye motion, and the head pivots to follow to try and create a naturalistic motion. Judge for yourself how well it works in the video below. (Jump to 7:15 for the finished product.)
For a farmer or gardener, fruit trees offer a way to make food (and sometimes money) with a minimum of effort, especially when compared to growing annual vegetables. Mature trees can be fairly self-sufficient, and may only need to be pruned once a year if at all. But getting the fruit down from these heights can be a challenge, even if it is on average less work than managing vegetable crops. [Kladrie] created this avocado snipper to help with the harvest of this crop.
Compounding the problem for avocados, even compared to other types of fruit, is their inscrutable ripeness schedule. Some have suggested that cutting the avocados out of the trees rather than pulling them is a way to help solve this issue as well, so [Kladrie] modified a pair of standard garden shears to mount on top of a long pole. A string is passed through the handle so that the user can operate them from the ground, and a small basket catches the fruit before it can plummet to the Earth. A 3D-printed guide helps ensure that the operator can reliable snip the avocados off of the tree on the first try without having to flail about with the pole and hope for the best, and the part holds the basket to the pole as well.
For those living in more northern climates, this design is similar to many tools made for harvesting apples, but the addition of the guide solves a lot of the problems these tools can have which is largely that it’s easy to miss the stems on the first try. Another problem with pulling the fruits off the tree, regardless of species, is that they can sometimes fling off of their branches in unpredictable ways which the snipping tool solves as well. Although it might not work well for avocados, if you end up using this tool for apples we also have a suggestion for what to do with them next.
Ever ruin a perfectly serviceable piece of toast by trying (and failing) to spread a little pat of rock-solid butter? [John Dingley] doesn’t! Not since he created the Butta Melta to cozily snug a single butter serving right up against a warm beverage, softening it just enough to get nice and spreadable. Just insert one of those foil-wrapped pats of butter into the Melta, hang its chin on the edge of your mug, and you’ll have evenly softened butter in no time.
The Butta Melta is intentionally designed with a bit of personality, but also has features we think are worth highlighting. One is the way it’s clearly designed with 3D printing in mind, making it an easy print on just about any machine in no time at all. The second is the presence of the hinge point which really helps the Butta Melta conform to a variety of cup designs, holding the payload as close as possible to the heat regardless of cup shape. A couple of minutes next to a hot beverage is all it takes for the butter to soften enough to become easily spreadable.
You may remember [John] (aka [XenonJohn]) from his experimental self-balancing scooters, or from a documentary he made about domestic ventilator development during COVID. He taught himself video editing and production to make that, and couldn’t resist using those skills to turn a video demo of the Butta Melta into a mock home shopping style advertisement. Watch it below, embedded just under the page break, then print one and save yourself from the tyranny of torn toast.
Capacitive touch sensors are entirely in the domain of DIY, requiring little more than a carefully-chosen conductive surface and a microcontroller. This led [John Phillips] to ask why not embed such touch buttons directly into a 3D print?
Button locations and labels can be made as part of the 3D print, which is handy.
The process is not much different from that of embedding hardware like magnets or fasteners into 3D prints: one pauses the print at convenient spot, drops in the necessary hardware, then resumes printing. It’s more or less the same for embedding a touch-sensitive button, but [John] has a few tips to make things easier.
[John] suggests using a strip of copper tape, one per touch pad, and embedding it into the print near the surface. His preference is three layers in, putting the copper tape behind 0.6 mm of plastic when using standard 0.20 mm layer heights.
Copper tape makes a good capacitive touch sensor, and the adhesive on the tape helps ensure it stays in place as the 3D printer seals it in on subsequent passes.
Copper tape is also easy to solder to, so [John] leaves a small hole over the copper — enough to stick in a wire and tack it down with the tip of a soldering iron and a blob of solder after the print is complete. It might not be ideal soldering conditions, but if things get a little melty on the back side it’s not the end of the world.
The flow battery is one of the more interesting ideas for grid energy storage – after all, how many batteries combine electron current with fluid current? If you’re interested in trying your hand at building one of these, the scientists behind the Flow Battery Research Collective just released the design and build instructions for a small zinc-iodide flow battery.
The battery consists of a central electrochemical cell, divided into two separated halves, with a reservoir and peristaltic pump on each side to push electrolyte through the cell. The cell uses brass-backed grafoil (compressed graphite sheets) as the current collectors, graphite felt as porous electrodes, and matte photo paper as the separator membrane between the electrolyte chambers. The cell frame itself and the reservoir tanks are 3D printed out of polypropylene for increased chemical resistance, while the supporting frame for the rest of the cell can be printed from any rigid filament.
The cell uses an open source potentiostat to control charge and discharge cycles, and an Arduino to control the peristaltic pumps. The electrolyte itself uses zinc chloride and potassium iodide as the main ingredients. During charge, zinc deposits on the cathode, while iodine and polyhalogen ions form in the anode compartment. During discharge, zinc redissolves in what is now the anode compartment, while the iodine and polyhalogen ions are reduced back to iodides and chlorides. Considering the stains that iodide ions can leave, the researchers do advise testing the cell for leaks with distilled water before filling it with electrolyte.
If you decide to try one of these builds, there’s a forum available to document your progress or ask for advice. This may have the clearest instructions, but it isn’t the only homemade flow cell out there. It’s also possible to make these with very high energy densities.
