Fantastic model by speedtwin69, however simplify3D did not slice the eyes properly. My modifications were extremely simple and done entirely in meshmixer.

This remix is for those who don't know how to do such things, as is the following guide to recreating it from the original using meshmixer:

1. In the Analysis tab, use the Inspector to repair any holes in the mesh
2. In the Edit tab, Close Cracks
3. In the Edit tab, use the Make Solid option with a Solid Type of accurate, and set the Solid Accuracy and Mesh Density sliders to max. Make sure you update and let it crunch the numbers, and like the outcome before accepting.
4. Go to File > Export to save the stl. Make sure you have the item denoted as (solid) in the floating Object Browser when exporting.