Making A Birthday Party Magical With Smart Wands

April 9, 2019 by Tom Nardi 11 Comments

Visitors to the Wizarding World of Harry Potter at Universal Studios are able to cast “spells” by waving special interactive wands in the air. Hackers like us understand that there must be some unknown machinations happening behind the scenes to detect how the wands are moving, but for the kids wielding them, it might as well be real magic. So when his son asked to have a Harry Potter themed birthday party, [Adam Thole] decided to try recreating the system used at Universal Studios in his own home.

Components used in the IR streaming camera

The basic idea is that each wand has a reflector in the tip, which coupled with strong IR illumination makes them glow on camera. This allows for easy gesture recognition using computer vision techniques, all without any active components in the wand itself.

[Adam] notes that you can actually buy the official interactive wands from the Universal Studios online store, and they’d even work with his system, but at $50 USD each they were too expensive to distribute to the guests at the birthday party. His solution was to simply 3D print the wands and put a bit of white prismatic reflective tape on the ends.

With the wands out of the way, he turned his attention to the IR imaging side of the system. His final design is a very impressive 3D printed unit which includes four IR illuminators, a Raspberry Pi Zero with the NoIR camera module. [Adam] notes that his software setup specifically locks the camera at 41 FPS, as that triggers it to use a reduced field of view by essentially “zooming in” on the image. If you don’t request a FPS higher than 40, the camera will deliver a wider image which didn’t have any advantage in this particular project.

The last part of the project was taking the video stream from his IR camera and processing it to detect the bright glow of a wand’s tip. For each frame of the video the background is first removed and then any remaining pixel that doesn’t exceed a set brightness level if ignored. The end result is an isolated point of light representing the tip of the wand, which can be fed into Open CV’s optical flow function to show [Adam] what shape the user was trying to make. From there, his software just needs to match the shape with one of the stock “spells”, and execute the appropriate function (such as changing the color of the lights in the room) with Home Assistant.

Overall, it’s an exceptionally well designed system considering the goal was simply to entertain a group of children for a few hours. We almost feel bad for the other parents in the neighborhood; it’s going to take more than a piñata to impress these kids after [Adam] had them conjuring the Dark Arts at his son’s party.

It turns out there’s considerable overlap between hacker types and those who would like to have magic powers (go figure). [Jennifer Wang] presented her IMU-based magic wand research at the 2018 Hackaday Superconference, and in the past we’ve even seen other wand controlled light systems. If you go all the way back to 2009, we even saw some Disney-funded research into interactive wand attractions for their parks, which seems particularly prescient today.

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Recreating Classic Model Kits With Modern Tech

April 5, 2019 by Tom Nardi 17 Comments

It used to be that if you wanted to make a nice scale model of an airplane, you’d be building the frame out of thin balsa ribs and covering it all up with tissue paper. Which incidentally was more or less how they built most real airplanes prior to the 1930s, so it wasn’t completely unreasonable to do the same on a smaller scale. But once injection molded plastics caught on, wood and tissue model kits largely went the way of the dodo.

[Marius Taciuc] wanted to share that classic model building experience with his son, but rather than trying to hunt down balsa kits in 2019, he decided to recreate the concept with modern techniques. His model of the Supermarine Spitfire, the vanguard of the British RAF during the Second World War, recreates the look of those early model kits but substitutes 3D printed or laser cut components for the fragile balsa strips of yore. The materials might be high-tech, but as evidenced by the video after the break, building the thing is still just as time consuming as ever.

Using a laser cutter to produce the parts would be the fastest method to get your own kit put together (you could even cut the parts out of balsa in that case), but you’ll still need a 3D printer for some components such as the propeller and cowling. On the other hand, if you 3D print all the parts like [Marius] did, you can use a soldering iron to quickly and securely “weld” everything together. For anyone who might be wondering, despite the size of the final plane, all of the individual components have been sized so everything is printable on a fairly standard 200 x 200 mm print bed.

While there’s no question the finished product looks beautiful, some might be wondering if it’s really worth the considerable effort and time necessary to produce and assemble the dizzying number of components required. To that end, [Marius] says it’s more of a learning experience than anything. Sure he could have bought a simplified plastic Spitfire model and assembled it with his son in an afternoon, but would they have really learned anything about its real-world counterpart? By assembling the plane piece by piece, it gives them a chance to really examine the nuances of this legendary aircraft.

We don’t often see much from the modeling world here on Hackaday, but not for lack of interest. We’ve always been in awe of the lengths modelers will go to get that perfect scale look, from the incredible technology packed into tiny fighter planes to large scale reproductions of iconic engines. If you’ve got some awesome model making tips that you think the Hackaday readership might be interested in, don’t be shy.

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The Fine Art Of Restoring Matchbox Cars

March 10, 2019 by Tom Nardi 25 Comments

Did you have anything planned for the next hour or so? No? That’s good because if you’re anything like us, watching even one of the restorations performed on [Marty’s Matchbox Makeovers] is likely to send you down a deep dark rabbit hole that you never knew existed. Even if you can’t tell the difference between Hot Wheels and Matchbox (seriously, that’s a big deal in the community), there’s something absolutely fascinating about seeing all the little tips and tricks used to bring these decades-old toy cars back into like new condition.

Sketching a replacement part to be 3D printed.

You might think that all it takes to restore a Matchbox car is striping the paint off, buffing up the windows, and respraying the thing; and indeed you wouldn’t be too far off the mark in some cases. But you’ve got to remember that these little cars have often been through decades of some of the worst operating conditions imaginable. That is, being the plaything of a human child. While some of the cars that [Marty] rebuilds are in fairly good condition to begin with, many of them look like they’ve just come back from a miniature demolition derby.

The ones which have had the hardest lives are invariably the most interesting. Some of the fixes, like heating up the interior and manually bending the steering wheel back into shape, are fairly simple. But what do you do when a big chunk of the vehicle is simply gone? In those cases, [Marty] will combine cyanoacrylate “super glue” with baking powder to fill in voids; and after filing, sanding, and painting, you’d never know it was ever damaged.

When a car needs more than just paint to finish it off, [Marty] will research the original toy and make new water slide decals to match what it would have looked like originally. If it’s missing accessories, such as the case with trucks which were meant to carry scale cargo, he’ll take careful measurements so he can design and print new parts. With some sanding and a touch of paint, you’d never know they weren’t original.

There’s plenty of arcane knowledge to be gained from folks like [Marty] who have experience with scale models. We don’t often see much of that come our way, but when we do, we’re always impressed at the lengths individuals will go to get that perfect end result. Whether or not you think you’ll find yourself rebuilding a pocket-sized school bus anytime soon, we think there are lessons to be learned from those who might. Continue reading “The Fine Art Of Restoring Matchbox Cars” →

Watch This LEGO Pantograph Carve Chocolate Messages

March 7, 2019 by Donald Papp 5 Comments

[Matthias Wandel] is best known for his deeply interesting woodworking projects, so you might be forgiven for not expecting this lovely chocolate-engraving pantograph made from LEGO. With it, he carves a delightful valentine’s message into a square of chocolate, but doesn’t stop there. He goes the extra mile to cut the chocolate carefully into a heart, and a quick hit with a heat gun takes the rough edges off for a crisp and polished end result.

The cutting end is a small blade stuck inside a LEGO piece, but that’s the only non-LEGO part in the whole assembly. A key to getting a good carve was to cool the chocolate before engraving, and you can see the whole process in the video embedded below.

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Lego Monorail From Your 3D Printer

February 16, 2019 by Jenny List 5 Comments

If you had to guess the age of a person hailing from a country in which Lego is commonly available, you might very well do it by asking them about the Lego trains available in their youth. Blue rails or grey rails, 4.5, 9, or 12 volt power, and even somewhat unexpectedly, one rail or two. If that last question surprises you we have to admit that we were also taken aback to discover that for a few years in the 1980s everybody’s favourite Danish plastic construction toy company produced a monorail system.

[Mike Rigsby] had a rather ambitious Christmas display to produce, and as part of it included a pair of reindeer, Rudolph and Bluedolph, atop freight cars on a loop of Lego monorail. He didn’t just use classic Lego parts off-the-shelf, instead he recreated the system in its entirety on his 3D printer; locomotive, rolling stock, and all. In a simlar way tot he original his locomotive sits between the two freight cars, each container housing a pair of AA batteries which together power the unit.

The Lego system isn’t perhaps a classic monorail, in that it involves a four-wheeled vehicle that is guided by a central rail rather than sitting upon it. Drive comes from teeth on the side of the rail which mesh with a gear on the power car. There have been 3D-printable sections of it available as add-ons for owners of classic sets for a while, but this may be the first printable locomotive and train. The Christmas novelty aspect of it all may be a little past its sell-by date here in February, but it’s still worth a look as a potential source of parts for any project that might require a linear rail system.

Perhaps surprisingly we’ve never featured a monorail before, though we have brought you a MagLev.

Make Your Lego Fly

February 10, 2019 by Richard Baguley 8 Comments

We probably all used to make our Lego fly by throwing it across the room, but Flite Test have come up with a slightly more elegant solution: they converted a Lego quadcopter to fly. They did it by adding a miniature flight controller, battery and motors/rotors to replace the Lego ones in the Lego City Arctic Air Transport kit. This combination flies surprisingly well, thanks to a thoughtful design that balances the heavier components inside the case.

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A Trove Of Cosplay Prop Making Tutorials And Blueprints

February 9, 2019 by Anool Mahidharia 5 Comments

[CutTransformGlue] recently posted a build video for “Making Rey’s Star Wars Blaster“, embedded after the break. The construction uses layered MDF sheets to build up the blaster, and it’s a treat to see it taking shape, ending with an amazing paint job. It’s a good way to learn about the techniques used to bring such props to life and help you hone your skills. But digging deeper led us down an awesome rabbit hole.

[CutTransformGlue] got plans for Rey’s Blaster from the Punished Props Academy – a prop and costume making team from Seattle committed to “transforming passionate fans into confident, skillful makers”. These folks have built a wide variety of projects ranging from guns, weapons, costumes, props and more, and are obviously extremely skilled at what they do. But they aren’t keeping those skills to themselves and in a series of posts and videos they are sharing with us such varied skills as Foamsmithing (gotta love that coinage), Molding, Casting, Painting, 3D printing, Vacuum Forming and electronics. If you’d like more information about supplies, check out the Tools and Materials section. And if all of this has given you the itch to build a Skyrim Wuuthrad or a Halo4 Sniper Rifle, head over to the amazing Free Blueprints section for a treasure chest full of downloads.

Like we said earlier, if building such stuff is your thing, it’s a rabbit hole from which you’ll find it extremely difficult to extract yourself. Have fun.

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