I could not get the idea of "GIMP as sculptor" out of my mind.

The first attempts were even worse than the one I'm submitting here.

On a new Grayscale image, I used only "Circle Fuzzy" brushes and "painted" ("daubed" really) on separate "Addition" and "Subtraction" layers above a 50-pct background gray layer to add and remove "height" with Values of 5 pct or 10 pct.
[Note at 10 pct, it only takes 5 daubs to get down to 0 or up to 100, after which you're done.]

It hit me that what I really want is a Paint-by-Number (Paint-by-Isoheights) which I could "bucket-fill" with appropriate grays.

Anyway, from this submission, you can at least imagine that Talent--or a medical illustrator--could pull it off.

Why yes, it IS a self-portrait. (Sadly, a near-perfect self-portrait.)

Looking for something else, stumbled upon (this one of) merrak's Great Idea(s):

http://gimpchat.com/viewtopic.php?f=11&t=3140

and recognized it immediately as The Solution for Sculpting Faces.

Anyone as old as I, familiar with old Superman comics knows, instinctively
knows that faces are composed of 3D polygons (there must be a word for them[1][2]):
doubters please refer to "Bizarro World/Htrae".

Thank you merrak for tying a bow in this. What is it you mathikers say?
"From here the solution is obvious..."

Get any old art book and turn to that page where it shows the human face
as a bunch of polygons, and make them and put them together and sculpt
them out a little and Violins! ugottaface.

(I will take a bow for suspecting a mathematician could easily solve this.
You have to read my prior posts carefully--and in a certain way--to see
where I suspected that. But it fair leaps out at me.)

Footnotes:
1. "Pyramids" maybe.
2. Is GimpChat reporting how many edits I've made on this one post?
If no, then forget I mentioned it.

I believe the new mesh for Blender utilizes trigon shapes.