Our second video moved us into some territory where we had to study a bit and pick up some new skills. We'd never used Arduinos before and had only ever done ultra basic electronics, so it was a great experience to learn how easy it is to make this stuff.
After a few months of tinkering and practicing, we came up with a design for this humidity sensor that would live in our shop. The purpose of it was to alert us to big swings in the Texas humidity so if we had an important woodworking project going, we could move it in the house or take other steps to not have it get all warped and messed up from the humid air.
It changes color depending on the humidity, so we could just open the door to the garage and peek in to see how things were doing. If it gets towards blue/purple light, it was super humid and time to move some stuff around.
It has a dovetailed walnut case and uses an Arduino Uno with some rad parts from Adafruit. Came out super cool. Give it a look!