This is a version of my original model Gear heart fidget toy keychain . In this version you don't need an extra part to secure the gears in place. The gear axes have 3 pins wich act like springs to let the gear through but spring back once the gears are completely through, holding them in place. 

Disclaimer: if you know your printer has trouble printing fine details or your prints suffer from poor layer adhesion, the pins might break. I'd recommend you print version 1 or version 2 of this same model.