Here is a model of a skull, made entirely freehand in 3D
-- using Blender---Open source software!

This stage took me the better part of 3 hours, checking proportions with my bone collection.
With practice, it will be done in much less time. The interior, however, will be much harder!

So 3D replaces paintings, illustrations? Not yet, but soon.
I've been working in 3D since 1983, and its finally coming into its own.