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

I created a todo thermal printer so that I can write messages whenever I remember something. For example when I'm lying in bed and I remember that I have to do something or reading a book and think that's a great thought that I should look more into someday.

Basically I have a mobile app that I can send a message to a api. Sometimes it's just a note, sometimes it is a todo item.

Then I have a raspberry pi that polls the api for new messages and prints them onto a receipt/thermal printer on my desk. Then every morning I usually look and see if there is a todo item, or more long term item.

I haven't exactly thought of how to store the messages, but basically when the "receipt" gets to CVS level, I rip it off and store it in in a document shelf organizer. Every few months I'll go through the receipt for any long term touch items.