Summary

Uses the fan motor to generate the current to supply 3 coloured 3mm LEDs.
Component used: 1 pcs 8x16x5 ball bearing, 1 pcs 10x16x0,5 mm flat washer, 3 pcs M12 nut, 3 pcs 3mm coloured LED, 1 pcs 24V fan motor and 3D printed parts.

More info: http://elettronicain.it/myMain/riviste/p_rivista.asp?nrRivista=EI218
https://www.open-electronics.org/category/opensourceprojects/