Corona Timer
Free     Thingiverse     Piepenbrink

Corona Timer

A small classroom project that reminds us to open the windows after 20 minutes It uses 3 10mm LEDs a button for reset an a piezo buzzer ...

similar models —

Corona Timer alternatives
Corona
AcEjbc
Corona Trophy
FunnyBot16
Corona Timer
Volker_P
Timer Knob
Shana