This QR code can "prank" your friends! Just print it in black first, and then switch to white for the last few layers. It can be easily printed on all types of 3D printers using any type of consumables! Place this QR code anywhere you want. When your friends and relatives can't resist the curiosity to take a look, you just need to stand by and watch them get "tricked" with amusement. Two sizes are included: large and small.