
I'm a bit of a fan for using Meshmixer and the tasks ahead of you are not particularly demanding, based on a rather important aspect of the model head. It's not unusual for a sculpting program to create extremely high detail, which results in a high facet/triangle/apex count. This is likely the reason that my Fusion 360 crashed on first attempt, followed simultaneously by Meshmixer. I rebooted and loaded the STL file or the OBJ file, can't recall which into Meshmixer from a clean start. You suggest in your post that you require a solid model. That's a different type of model within Meshmixer and it may be that you do not require a solid model so much as you require a manifold or watertight model.


The models you've provided are indeed manifold and do not fail the typical test for such properties. Mesh enabler for inventor 2018 software#.
