3D printing a stunning silver mechatronic beetle necklace

CNC milling is expensive, messy, and requires a lot of technical knowledge, which is why we all want the ability to 3D print metal. But while technologies like SLS metal printing do exist, they are generally out of reach of hobbyists. Fortunately, there is a secret third option: investment casting. Formlabs makes casting resins specifically for that job, which Allie Katz and DJ Harrigan (AKA Mr. Volt) used to create this stunning mechanic beetle necklace in silver.

Katz and Harrigan made this at a hackathon that Formlabs hosted, so they were able to take advantage of the available printers, resins, and in-house casting expert. The necklace features a large silver beetle resting on a pair of leaves designed to lay across the wearer’s sternum. When the beetle detects heat, such as from a person approaching, it opens its wings to reveal a colorful array of LEDs like stained glass on its thorax, while it wiggles its antennae.

The leaves were printed in flexible resin, while the silver parts were printed in casting resin. The latter then went into a plaster investment casting mold and were filled with molten silver. After cooling, they were cleaned and carefully polished to a shine.

The beetle’s electronic functions operate under the control of an Arduino Nano 33 BLE board. It looks for heat signatures through a thermal camera module. Based on that input, it actuates the three tiny servo motors and the 35 individual RGB LEDs.

The result is beautiful and the beetle’s silver carapace really couldn’t be produced by automated means in any other way.