Boundless 3D's Four-Key Macropad Is Print-in-Place — Thanks to Conductive Filament and an AMS

Pseudonymous maker "Boundless 3D" has been experimenting with conductive filament for fused filament fabrication (FFF, also known as FDM) 3D printers — culminating in the creation of a four-key print-in-place macropad.

"Conductive filament is one of the more unique materials you'll come across when you 3D print," Boundless 3D says by way of introduction to his recent experimentation, "but it's rarely used. I think a large part of that is there's not many designs that actually take advantage of that conductive property. So, let's see if we can change that."

Conductive inks mix an electrically-conductive material with ink to allow you to draw circuits; conductive filaments likewise mix an electrically-conductive material with PLA or another 3D-printable plastic to allow you to print circuits directly. They're most useful in a printer with multi-material support, but can also be used with manual material changes and careful design — but a circuit made from conductive filament can't be soldered to, limiting its usefulness.

Boundless 3D's experiments with conductive filament began with simple tests as to its conductivity, printing various thicknesses and measuring their resistance. From there, he built a battery adapter and a work-in-progress (not-quite-working-yet, at the time of writing) electromagnet — but it's the third experiment that may prove the most useful: a working print-in-place four-key macropad.

"It's an awesome feeling to take your print off the printer, plug it into the computer, and have it do something," the maker says of the device, which uses a 3D-printed socket to connect an Arduino Micro or compatible microcontroller development board to four pads acting as capacitive touch sensors — all printed in one go, using a multi-material-capable FFF printer.

Boundless 3D has uploaded 3D print and STEP files for the macropad to Printables, under the reciprocal Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International license. "This project is still experimental," the maker admits, "but functional, and at a good point to share it with the community to see what they'll do with it."