Ask HN: Most interesting tech you built for just yourself?

I have been struggling with my circadian rhythm and have been exploring light therapy and novel techniques that will help me wake up. I learned that a smart light I bought, from Kasa, has a solid community written python library that controls it on the local network. I made a little app that adjusts the lamp color based on sunrise and sunset hours. It's relatively simple technology wise, but it's forced me to rethink how I evaluate "smart" technology.

I am thinking of expanding it to be a notification light of sorts. Not for anything related to the internet, but for chores, like the laundry machine finishing, or reminders to take a break from work. It's helped me remember to grab lunch more than a few times this week. There's something pleasant about light notifications compared to vibrations or sounds.

I am working on making an advanced wifi enabled timer using an esp32. I love the idea of a dedicated timer, seperate from my phone, that I can use day to day. I have a basic display and webserver for scheduling countdowns/alarms, but I want to incorporate some sort of keypad and a couple input buttons. There's plenty of ways in can be improved.

I also have a first generation raspberry pi monitoring my washing machine, it sends me notifications when a cycle finishes. It uses a simple ultrasonic sensor and is hosting a web server showing a readout.