Things I have thought about working on, and things I have started working on, but probably not things I have finished

Tube button - An old Jubilee Line door button, take out the insides and use it as a switch for something

Home environmental monitoring - BME680 board, with results sent to MariaDB and Grafana

GPO phones - Trying to get old General Post Office telephones working with VOIP

Nextion display - A programmable touchscreen, might make a nice control panel for something