This model is a Gengar hanging charm / keychain! This version has hollow eyes and mouth.
This charm is 9cm wide, 8cm tall and is 6mm thick.
Charms are designed with a 'channel' to allow for a 2.4mm (or smaller) ball chain to be looped through. Ball chain is available very cheap online in a variety of colours - we suggest cutting the ball chain to a length of 25cm.
To print the back of the two sided version perfectly, colour it in your slicer and set the height on the bed 0.2mm lower than default.