This is a rack and pinion for a linear actuation on an MG995R servo.

This is a standard 40x20mm servo.
The gear is designed to fit snugly onto the metal part of the servo.
You will need some M2 screws and bolts if you want to permanently attach the mount, which I reccomend highly.

I hope this helps anyone. I made this for a syringe pump, which works great with this addition!