Most electronic designs focus on a printed circuit board's function. Considerations about form are usually limited to "does it fit in the enclosure." The latest project from Debra Ansell of Geek Mom Projects combines form and function with PCBs creating an articulated chain that passes power, ground, and data. And of course the data line controls NeoPixels!
Ansell's overall design consists of two assemblies. There is a control piece and multiple chain links. Chain links consist of multiple parts. A few plastic bits help maintain the overall structure, but the most used material is PCBs.
There is an ATtiny1614 microcontroller, two coin cell batteries, and a push-button on the control board. The chain link boards connect to the control board through a press-in snap connector with 10 conductors. However, some of those pins are redundant because power, ground, and one data line are the only necessary signals.
The chain links are an assembly with two PCBs, an acrylic spacer, and a plastic retention piece. On the top PCB piece, one side has three 2020-case sized NeoPixels, while the other side has three metal rings. These represent the power, ground, and signal.
Those three pads make contact with six pressure contacts on the bottom PCB piece. (There are two contacts for each ring for redundancy.) Because the pressure contacts are fragile, Ansell laser cut an acrylic piece that removes some of the mechanical strain on the connections.
From the original Geek Mom Projects' Twitter thread, followers asked (at least) two great questions. The first person brought up the somewhat small Blingy-Ratio.
And the second asked if the board ran Python. (It took us a second, or third, read to get the joke, as well.)
Ansell is still working on explanation content. For now, she has an excellent video that walks through the design of the boards.