These are replacement lenses for the awesome Adafruit NeoPixel Goggles (https://www.adafruit.com/products/2221). The lenses include a dualstrusion "camera iris" style design. I printed these in black ABS designs over clear PLA lenses. They show the LED animations really well. Just unscrew the goggles cap, pull out the various lenses, and replace with these. One design is flipped, so you don't have to do it in software.