Create a digital inventory of your trading/collectible cards using Lego and a Raspberry Pi.
You can use ML tools from AWS and connect them to a Raspberry Pi to ID birds at your bird feeder.
Build a facial recognition camera that can detect if someone is smiling (or not) and their age using Wia, Amazon Rekognition & Raspberry Pi.
At Coolest Projects 2018, we showcased the Wia platform with a facial recognition Ferris wheel!
I combine an Arduino camera, AWS Lambda and Rekognition, and an Amazon Echo to determine if I've left the washing on my clothes line!