Screen-free perpetual desk calendar. For anyone who wants the date without a screen: thumb the drums each morning to set weekday, date and month, drop paperclips and keys in the rear tray, and stand a pen in the bore. No batteries, no app, and it resets every day for years.

Four drums, three windows. Three front windows read DAY, DATE and MONTH. Four 1.4 in drums spin independently on 0.24 in axle pegs: weekday, date tens, date units and month. Knurled bands at both ends of every drum give your thumb grip, and a flexing pawl rides a 0.047 in tooth ring so each step lands with a click.

Seven parts, one screwdriver.