This is a modification of a "Parking Assistant" I found on "Intructables.com".(https://www.instructables.com/id/Arduino-Parking-Assistant/)

His version is in a wooden case and he does a nice job explaining how to create the case. My version is in a 3D printed case I designed using "FreeCad" (Thanks FreeCad!)

His version uses discrete leds. My version uses a neopixel ring from adafruit (WS2812) (https://www.adafruit.com/product/1463) I modified his Arduino code to use the WS2812 led ring.

His version uses an Arduino pro mini My version uses a "Trinket" from adafruit (https://www.adafruit.com/products/1501)

We both use the HC-SR04 sonic sensor (https://www.amazon.com/Organizer-Ultrasonic-Distance-MEGA2560-ElecRight/dp/B07RGB4W8V/ref=sr_1_6?dchild=1&keywords=HC-SR04&qid=1605536977&sr=8-6)

We both use a push button to set the initial parking distance. These are similar to the one I used. (https://www.adafruit.com/products/1119)