A fix of my Lamy Pico pen using a replacement brass part. The original part had broken on a plastic thread. The internal parts of that broken part were re-used in the new replacement part. ... https://www.youtube.com/watch?v=1FCgOIUc_Lo

This uses a casio fx-502p and and Arduino to control the flashing of a light bulb. The light bulb is an old Belisha beacon (https://en.wikipedia.org/wiki/Belisha_beacon) that I dug up in my garden, I've no idea how it got there. The bulb is a 60W mains filament type that is driven by a BTA204 triac which is in turn driven by a MOC3041 which is driven by a transistor attached to one of the digital outputs of an Arduino Due. The Due flashes the lamp at a particular rate, the rate being set by a Casio fx-502p. The Casio sends a data stream in Kasas City type format to an Arduino shield on the Due that turns the 1200/2400Hz signals into square waves, the Due code then decodes that into numbers. One of the numbers (the 'file number', the Casio's equivalent of a file name) is used to control the half-period of the flashing cycle The bottom two digits are used so 0 to 99 is approximately 2Hz to 0.5Hz. ... https://www.youtube.com/watch?v=dzFQdBvnSlo