Droppy Micro

Just a servo dropper ... could be used for anything even as lock. Fits most mini servos..
I suggest to print it with 100% infill and make sure the holes aren't getting too tight, in case its a good idea to tap em with a M3 male tap.
It fit's most mini servo that are 23mm large but if you want to go the safe way then you could get the same servos i am using which are these. https://goo.gl/l643wk