An idea of a blinking earring was born while talking at the local hackerspace. Inger was playing with harddisk parts and wanted to make blinking earrings. She has been doing workshops making jewelry from old computer parts (very, very nice; she is not an engineer/technician).
Well, we were discussing a more advanced version and this is what I came up with and how it looks (31mm outer diameter)
The paperclip trick was inspired from matseng’s idea (many thanks!) and it uses a standard cr2032 battery.