What have you used a RaspberryPI/Arduino for?

I bought a couple of 64x64 LED Matrix displays and used an ESP32 to control the display of images on it.

It now makes a cool feature in my room

https://github.com/bradleeharr/Image-Display-LED-Matrix

https://github.com/bradleeharr/Perlin-Noise-LED-Matrix

Testing circuits I’ve made on a breadboard.

I have some addressable LED strips that I want to put on my car and make a stream of hearts and stars as I drive past or overlay my car (for one moment) with an Acura NSX or something like that. I got stuck developing a test framework for it (can’t test it fully in motion) and never figured out a good way to set it up in the car but really I should ‘just do it’.

College senior project - 3dof robotic arm on a vertical gantry system attached to a hydroponic garden. We used 2 arduino’s to control the lighting and gantry. Then one pi onboard the robot for imaging and another for a web user interface.

Powering TV displays at work with a simple script using feh and Syncthing for copying files over to the pi's around the factory

Vex robotics kit driver for camera gimbal, ir Bridge, Bluetooth alarm clock, x10 bridge.

Raspberry Pi dedicated to just 2 jobs: Web Server and UPS controller.

Air quality monitoring.

home fleet of security cameras