How can the big box store mix the perfect shade of English Wedgwood right before your eyes? The answer is in highly-concentrated pigments that come in many different sizes up to a whopping five gallons. Now, just imagine the amount of watercolor, acrylic, or other types of paint that could be made by simply scraping the walls of an empty 5-gallon tub, which you know is just getting thrown away with all that usable pigment inside.
The process will likely take the form of an open-source three-roller milling machine, which are commonly used in paint manufacture. Basically you have three rollers that process the pigment and binder, and the mixture is run through as many times as necessary. Although they are fairly simple machines in design, building them to work well requires adherence to precise technical specs.
We can’t wait to see what [technoplastique] comes up with to use for the stainless steel rollers. The rest of the plan involves a Raspberry Pi Pico, one DC motor per roller, a motor shield, and a power supply, but the rollers are pretty crucial. If you have any ideas other than steel rolling pins (the kitchen kind) or pipe couplings (which are too short, anyway), let us know in the comments!
We’ve all learned in primary school art classes that blue and yellow make green, and that adding a little black to a color will make it darker. But what if you want to paint with a color that exactly matches something else? Usually, that requires a lot of trial and error (and paint), and the end result may not look the way you wanted after all.
To help aspiring artists, [Airpocket] made the M5Stack Color Maker. This is a device that reads out a color sensor and automatically mixes watercolor paint in the right proportions to match what it sensed. It dispenses drops of cyan, magenta, yellow and black paint (CMYK) into a small bowl, from which you can then apply it with a paintbrush.
The color sensor is similar in use to the color picker (or “dropper”) tool present in most graphics programs: simply point it at something that has the right color, and it will generate the correct values for you. It is based on an AMS TCS34725 color sensor, which is housed in a 3D-printed shell that also includes a white LED. The sensor outputs Red, Green and Blue (RGB) values, which are converted into the corresponding CMYK values by a Raspberry Pi Pico. A touch-sensitive screen allows the user to make adjustments before activating the paint pumps.
Those pumps are tube pumps, which have been specifically designed (and also 3D printed) to allow them to move tiny amounts of liquid while minimizing the pulsing motion typical with this type of pump. They are driven by stepper motors which are controlled by the Pi Pico.
In Banksy’s book, Wall and Piece, there is a very interesting quote; “Imagine a city where graffiti wasn’t illegal, a city where everybody could draw whatever they liked…”. This sounds like it would be a very exciting city to live in, except for those of us who do not have an artistic bone in their body. Luckily, [Niklas Roy] has come up with the solution to this problem; the Graffomat, a spray can plotter.
The Graffomat is, in its creator’s own words, a “quick and dirty graffiti plotter.” It is constructed primarily from wood and driven by recycled cordless drills that pulls string pulleys to move the gantry. The Arduino Nano at the heart of the Graffomat can be controlled by sending coordinates over serial. This allows for the connection of an SD card reader to drip-feed the machine, or a computer to enable real-time local or over-the-internet control.
We are especially impressed with how [Niklas] handled positional tracking. The cordless drills were certainly not repeatable like a stepper motor, as to allow for open-loop control. Therefore, the position of the gantry and head needed to be actively tracked. To achieve this, the axes are covered with black and white striped encoder strips, that is then read by a pair of phototransistors as the machine moves along. These can then be paired with the homing switches in the top left corner to determine absolute position.
As cool as resin-based 3D printers are, they’re not without their shortcomings. One sore point, especially for those looking to document their prints, is that the translucent resins often favored for stereolithography can make the finest details difficult to see. Injecting paint into the model is how [Andrew Sink] decided to attack this problem, and the results are pretty striking.
For sure, this isn’t a problem that everyone making resin prints is going to face. Some resins are nicely opaque, and the fine details of a print show up just fine. But transparent resins lend a nice look to some projects, and might benefit from [Andrew]’s technique. It’s pretty much as simple as it sounds: choose a hollow model — or modify an existing one — print it up in the usual way, and clean thoroughly inside and out with isopropanol before curing under UV. Using a curing station that can get UV light up into the voids is probably a smart idea.
To finish off, the cured model is injected with acrylic paint. Nothing special here, just craft store acrylic in a syringe. [Andrew] seemed to prefer a thicker paint; we don’t want to second guess, but intuitively a thinner paint would seem to have some advantages. In any case, be sure to provide adequate vent holes for the displaced air. The video below has a few before and after shots, and the technique really works well to show off surface detail. Plus it just plain looks cool.
This seems like a good technique to keep in mind, and might even work well for hollow FDM prints done with transparent filaments. Still on the fence about FDM vs. SLA? We can help with that.
To say that that the commercially available garden path lights commonly available at dollar stores are cheap is a vast overstatement of their true worthlessness. These solar-powered lights are so cheaply built that there’s almost no point in buying them, a fact that led [Mark Presling] down a fabrication rabbit hole that ends with some great tips on powder coating parts with difficult geometries.
Powder coating might seem a bit overkill for something as mundane as garden lights, but [Mark] has a point — if you buy something and it fails after a few weeks in the sun, you might as well build it right yourself. And a proper finish is a big part of not only getting the right look, but to making these totally un-Tardis-like light fixtures last in the weather. The video series below covers the entire design and build process, which ended up having an aluminum grille with some deep grooves. Such features prove hard to reach with powder coating, where the tiny particles of the coating are attracted to the workpiece thanks to a high potential difference between them. After coating, the part is heated to melt the particles and form a tough, beautiful finish.
But for grooves and other high-aspect-ratio features, the particles tend to avoid collecting in the nooks and crannies, leading to an uneven finish. [Mark]’s solution was to turn to “hot flocking”, where the part is heated before applying uncharged coating to the deep features. This gets the corners and grooves well coated before the rest of the coating is applied in the standard way, leading to a much better finish.
We love [Presser]’s attention to detail on this build, as well as the excellent fabrication tips and tricks sprinkled throughout the series. You might want to check out some of his other builds, like this professional-looking spot welder.
The new “whitest white” paint comes to us from Purdue University in the US. It’s capable of reflecting 98% of sunlight reaching its surface, a big step up over the typical 80-90% of conventional white paints. Additionally, it doesn’t absorb UV light, and can also radiate out heat in infrared wavelengths that pass out of the atmosphere. This allows the paint to cool surfaces below ambient temperature. The paint achieves these feats by using barium sulphate as a pigment, which doesn’t absorb UV like conventional titanium dioxide white pigments do. The paint also uses a lot of pigment – 60%, versus 20-40% in a more typical paint. This is similar to techniques used in producing Vantablack, the blackest black acrylic paints.
The hope is that by painting roofs and walls of buildings with white paint, more sunlight will be reflected back out into space, and buildings will be naturally cooler with less reliance on air conditioning, helping to reduce emissions. This could go a long way to solving the heat island effect in many major cities. Municipalities around the world have already begun adopting the technique, from California, to New York and Ahmedabad. It’s an easy thing to do, with few drawbacks, so we expect to see the practice grow more popular in coming years. While it won’t solve the climate crisis on its own, the world could surely use every bit of help it can get.
If we cast our minds back a few decades, almost all computers were a beige colour. “Beige box” even became a phrase for a generic PC, such was their ubiquity. Long before PCs though there were other beige computers, and probably one of the first to land on the desks of enthusiasts rather than professionals was the Apple ][. But exactly what beige colour was it? It’s a question that interested [Ben Zotto], and his quest led him through a fascinating exploration of a colour most of us consider to be boring.
We’re used to older beige computers becoming yellow with time, as the effect of light and age causes the fire retardants in their plastic to release bromine. But the earlier Apple products haven’t done this, because their beige came not from the plastic but from a paint. [Ben] was lucky enough to find a small pot of touch-up paint from Apple that was made available to dealers, so notwithstanding any slight pigment changes from its age, he set off in pursuit of its origin.
Along the way to identifying a modern Pantone shade (Pantone 14–0105 TPG, for the curious) he treats us to a cross-section of Apple’s early colour history with reference to the memories of early Apple luminaries. He even suggests readily available shades that could suffice, pointing to Gloss Almond Rust-Oleum spray paint.