My version of using 2 servos, some dental floss and ping pong balls to create moving eyes. Original used some plastic cups, unknown balls and wooden Popsicle sticks. Wanting to get more skills with using FreeCAD as opposed to Fusion 360 I made this.

The latest update, version 3, should be final. I had to move the rear servo out 4mm so the tendon/floss cleared the guide hole well. I didn't change the eye sockets so they are still listed with the number 2.

Creality

Ender 3

No

No

0.2

40%

prints pretty easily.

I went through 3 iterations to get to the current point with the last changes being hollowing out behind the eyes(eye sockets) so LED/lighting could be added easily, putting the tendon/floss guide hole in the side of the first servo mount along with alignment pins/holes to keep the eye socket part aligned easily when adding hot glue. I also add a dab of hot glue on a side corner and bottom of each servo just to keep it in place and tight since I'm only using one screw to hold them down. I included the SG90a design file since the one in the FreeCAD library was too small and seemed to miss that there's an injection molding draft to the case and it's larger on the bottom than on the top. Animate with a couple of servo testers, an arduino and joystick, a Raspberry Pi, etc.