Here’s an eye mechanism I modelled in freeCAD. It includes small parts to test adhesion of your build plate but if it won’t stick, either slow the speed down by a lot or print separately just in case. The mechanism works by one big gear moving two ‘pokers’ that moves the left and right only. This is for a potential penguin animatronic im building but you can use it on anything. Keep checking my profile because I’m modelling a dc motor so you can make it fully electric and more accessible than other servo builds. Good look and feel free to download the model!