Conductive filament isn’t an ideal electrical conductor, but it’s a 3D-printable one and that’s what makes [Hercemer]’s 3D-printed flashlight using conductive filament work. Every part of the flashlight is printed except for the 9 volt battery and LEDs. Electrically speaking, the flashlight is a small number of LEDs connected in parallel to the terminals of the battery, and turning it on or off is done by twisting or loosening a cap to make or break the connection.
The main part of the build is a 3D-printed conductive cylinder surrounded by a printed conductive ring with an insulator between them. This disk- or pad-shaped assembly forms not only the electrical connection between the LEDs and battery terminals, but also physically holds the LEDs. To attach them, [Hercemer] simply melts them right in. He uses a soldering iron to heat up the leads, and presses them into the 3D-printed conductive block while hot. The 9 V battery’s terminals contact the bottom when the end cap is twisted, and when they touch the conductive assembly the flashlight turns on.
Anticipating everyone’s curiosity, [Hercemer] measured the resistance of his conductive block and measured roughly 350 ohms when printed at 90% infill; lower infills result in more resistance. You can see a video of the assembly and watch the flashlight in action in the video, embedded below.
We would love to be a fly on the wall Christmas morning to see [Wilksyonreddit]’s kid tear the paper off of this adult-level busy box. Can you imagine the unbridled glee? It should certainly make the arduous six-month build worth the trouble. Here’s hoping the walls are sturdy, because we predict they will be bounced off of.
This gift that keeps on giving has an Arduino MEGA clone inside and a couple of shift registers to deal with all those buttons and switches. In addition to all the buttons, switches, and the number pad, there are two 3D-printed touch sensor pads that can detect little fingers up to four inches away. Although he’s already built a few games and activities for it, [Wilksy] posted this in r/duino looking for more ideas. There’s a lot to work with here on baby’s first nuclear missile launch console, both input- and output-wise. We humbly suggest 4D Simon, though we must admit to fantasizing about MIDI controllers.
Hidden inside this Christmas present is an Easter egg we think you’ll appreciate. Enter the right code, and the box becomes a treasure trove of Back to the Future sound effects and audio clips. Video’s after the break, McFly.
This box would make a great Kerbal Space Program controller, too, like this one.
If you’ve ever wanted to more fully integrate yourself with technology, you might have to thank a team of researchers — led by [Michael McAlpine] — at the University of Minnesota in the near future. They’ve developed a technique that allows circuits to be printed directly onto your skin, with the team arguing — once the low-cost printer is modified for compact portability — it would be ideal for ‘on-the-fly’ circuit needs.
“But the hand isn’t exactly a stable print bed,” you say. We hear you, and the team is actually one step ahead — the printer can compensate for subtle movements during the printing process by tracking markers placed on the hand. The ‘filament’ is made from silver flakes — akin to conductive ink — which prints and cures at room temperatures, and can be either peeled or washed off. We should hope so, as it’s meant to be layered on human skin.
Speaking of which, it can also print cells!
It’s only been tested on a mouse so far, but the same technology that allows the printer to accurately track the hand means that it could use bio-ink to directly add cells to a wound or some other epidermal affliction to help speed the healing process.
For the circuits, though, you’ll still need the other circuit components and a compact means to power them — to say nothing about the fact that if the circuit is water-soluble, then a little perspiration would cause the ink to run. We’re excited to see where this tech goes!
One of the problems encountered thus far with 3D-printing circuits with conductive filament is that it doesn’t really bond to anything, let alone solder, so how does one use it?
[mikey77] wrote an Instructable showing how to print circuit boards and create simple circuits, using shape of the plastic as a way to control the circuit. We like how he used using the flexible nature of the filament to make buttons, with two layers of conductive material coming together with the press of a finger.
He also created a linear potentiometer with a 3D-printed wiper that increases the ohms of the connection the farther it’s pushed. The filament doesn’t have the same conductivity as copper so [mikey] was able make resistors by stringing pieces of conductive plastic between two leads. There are also some hexagonal touch pads that turned out very nice.