The article says he had “a” neopixel ring lying around. Not sure where the HaD writer got several. Also, these rings are $2.70 per pair on Aliexpress, meaning 8 could be as little as $10.80 ...

Inside the printed puck is an Arduino Nano running an MPU6050 accelerometer, a 12-NeoPixel ring, and a piezo buzzer. [DIY_Maxell] reused a power bank charging circuit to charge up the small LiPo ...