Building A Light That Reacts To Radio Waves

When it comes to electromagnetic waves, humans can really only directly perceive a very small part of the overall spectrum, which we call “visible light.” [rootkid] recently built an art piece that has perception far outside this range, turning invisible waves into a visible light sculpture.

The core of the device is the HackRF One. It’s a software defined radio (SDR) which can tune signals over a wide range, from 10 MHz all the way up to 6 GHz. [rootkid] decided to use the HackRF to listen in on transmissions on the 2.4 GHz and 5 GHz bands. This frequency range was chosen as this is where a lot of devices in the home tend to communicate—whether over WiFi, Bluetooth, or various other short-range radio standards.

The SDR is hooked up to a Raspberry Pi Zero, which is responsible for parsing the radio data and using it to drive the light show. As for the lights themselves, they consist of 64 filament LEDs bent into U-shapes over a custom machined metal backing plate. They’re controlled over I2C with custom driver PCBs designed by [rootkid]. The result is something that looks like a prop from some high-budget Hollywood sci-fi. It looks even better when the radio waves are popping and the lights are in action.

It’s easy to forget about the rich soup of radio waves that we swim through every day.

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A man cutting wood with a circular bench saw

Ultimate Picture Frame Combines Walnut And 3D Printing

[Make Something] boasts he has made probably the fanciest picture frame you’ll ever see. He started with an original sign purchased on eBay and then made it to be bigger, brighter, and better. The frame is of solid walnut with back-lighting for the imagery all chasing that classic mid-century modern style. The backlit photo was taken the “hard way”, with an actual film camera and a road-trip to the picturesque site at Yellowstone. [Make Something] then developed the film himself in his home studio.

For the chimney [Make Something] used a new trick he learned in Autodesk Fusion: you take a photo of an object, convert to black and white, and then use the light/dark values to emboss or deboss a surface. To do this he took photos of the brick wall outside his shop and used that as the basis of the textured chimney he made with his 3D printer.

If you’re interested in other projects made from solid walnut, check out 3D Printed Spirograph Makes Art Out Of Walnut and Walnut Case Sets This Custom Arduino-Powered RPN Calculator Apart From The Crowd.

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X-Cube Prism Becomes Dichroic Disco Ball

You’ve likely seen an X-cube, a dichroic prism used to split light into its constituent colours–you know, those fun little cubes you get when tearing apart a broken projector. Have you considered that the X-cube need not be a cube for its entire existence? [Matt] at “Matt’s Corner of Gem Cutting” on YouTube absolutely did, which is why he ground one into a 216-facet disco ball. 

That’s the hack, really. He took something many of us have played with at our desks thinking “I should do something cool with this” and… did something cool with it that most of us lack the tools and especially skills to even consider. It’s not especially practical, but it is especially pretty. Art, in other words.

The shape he’s using is known specifically to gemologists as “Santa’s Little Helper II” though we’d probably describe it as a kind of isosphere. Faceting the cube is just a matter of grinding down the facets to create the isosphere, then polishing them to brilliance with increasingly finer grit. This is done one hemisphere at a time, so the other hemisphere can be safely held in place with the now-classic cyanoacrylate and baking soda composite. Yes, jewelers use that trick, too.

We were slightly worried when [Matt] dumped his finished disco ball in acetone to clean off the cyanoacrylate– we haven’t the foggiest idea what optical-quality glue is used to hold the four prisms of an X-cube together and were a little worried acetone might soften the joints. That turned out not to be an issue, and [Matt] now has the most eye-catching sun-catcher we think we’ve ever seen.

We actually have seen suncatchers before, though admittedly it’s not a very popular tag around here. The closest build to this one was a so-called “hypercrystal” that combined an infinitiy mirror with a crystaline shape and dicloric tape for an effect as trippy as it sounds.

We also featured a deep-dive a while back if you want to know how these colourful, hard-to-pronounce coatings work.

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Redneck Spaceship From Trash

Facebook Marketplace provides you with a free grain silo, so what do you do with it? If you are [saveitforparts], you mix it with other materials and produce a retro-style rocket ship prop. Art project? Sure, we’ll call it that.

We have to admit, we also see rockets in everyday objects, and the silo does look the part. He also had some junk that looked like a nose cone, some tanks, and other assorted trash.

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Christmas Ornament Has Hidden Compartment, Clever Design

If you need something clever for a gift, consider this two-part 3D-printed Christmas ornament that has a small secret compartment. But there’s a catch: the print is a challenging one. So make sure your printer is up to the task before you begin (or just mash PRINT and find out).

Want a challenging print that’s also useful? This two-piece ornament has a small gift area inside, and prints without supports.

This design is from [Angus] of [Maker’s Muse] and it’s not just eye-catching, but meticulously designed specifically for 3D printing. In fact, [Angus]’s video (embedded under the page break) is a great round-up of thoughtful design for manufacture (DFM) issues when it comes to filament-based 3D printing.

The ornament prints without supports, which is interesting right off the bat because rounded surfaces (like fillets, or a spherical surface) facing the build plate — even when slightly truncated to provide a flat bottom — are basically very sharp overhangs. That’s a feature that doesn’t generally end up with a good surface finish. [Angus] has a clever solution, and replaces a small section with a flat incline. One can’t tell anything is off by looking at the end result, but it makes all the difference when printing.

There are all kinds of little insights into the specific challenges 3D printing brings, and [Angus] does a fantastic job of highlighting them as he explains his design and addresses the challenges he faced. One spot in particular is the flat area underneath the hang hole. This triangular area is an unsupported bridge, and because of its particular shape, it is trickier to print than normal bridges. The workable solution consists of countersinking a smaller triangle within, but [Angus] is interested in improving this area further and is eager to hear ideas on how to do so. We wonder if he’s tried an approach we covered to get better bridges.

Want to print your own? 3D files are available direct from [Angus]’s site in a pay-what-you-like format. If your 3D printer is up to it, you should be able to make a few before Christmas. But if you’d prefer to set your sights on next year with something that uses power and hardware, this tiny marble machine ornament should raise some eyebrows.

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One of four MDF half-tone blocks coming off the laser cutter.

Laser Cutter Plus CYMK Spraypaint Equals Full-Color Prints

This is one of those fun hacks that come about from finding a product and going “I wonder if I could…” — in this case, artist/YouTuber [Wesley Treat] found out his favourite vendor makes spray cans in CYMK colours– that is the Cyan, Yellow, Magenta and blacK required for subtractive printing. Which got him wondering: can I make full-colour prints with this paint?

MDF block print
The MDF-based print, with naive half-tone dots.

His answer was “yes”, and the process to do so is fairly simple. First, split the image into colour channels, generate a half-tone pattern for each one, and carve it out of MDF on the laser. Then spray the MDF with the appropriate colour spray paint. Press the page against each block in turn, and voila! A full colour print block print, albeit at very low DPI compared to your average inkjet.

Now, you might be wondering, why half-tone instead of mixing? Well, it turns out that these CYMK paints are too opaque for that to work in a block-printing process. At least with a naive spray technique; [Weseley] does admit a very fine mist might be able to make that work. The second question is why not just hook the rattle cans into a CNC machine for a paint-based mega inkjet? That’s a great question and we hope someone tries it, but [Weseley] evidently likes block-printing so he tried that first.

The Mylar stencil print, with a more artistic half-tone pattern.

Laser-ablating enough MDF away to make decent print blocks took too long for [Weseley]’s tastes, however, so he switched to using mylar stencils. Instead of spraying a block and pressing onto it, the paint is sprayed through the stencil. The 10 mil Mylar not only cuts faster, but can support finer detail. Though the resulting prints lose some of the artistic flair the inconsistencies block printing brings, it probably looks better.

If you prefer to skip the manual paint-can-handling, perhaps we can interest you in a spray-can plotter. If you do like manually flinging paint, perhaps you could try this dot-painting spray can attachment, for a more self-directed half-tone.

Thanks to [Keith Olson] for the tip.

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Trace Line Clock Does It With Magnets

We love a good clock project, and [byeh_ in] has one with a design concept we don’t believe we have seen before. The Trace Line Clock has smooth lines and a clean presentation, with no sockets or visible mechanical fixtures.

Reading the clock is quite straightforward once one knows what is going on. At its heart, the unmarked face is much like any other analog clock face, and on the inside is a pretty normal clock movement. The inner recessed track on the face represents hours, and the outer is minutes. The blue line connects the two, drawing a constantly changing line.

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