I've used trandoductins link HOW TO CREATE POLYGON ART IN GIMP.
I don't know if i did it right. It's my first try.

Ella, that is beautiful. Hard to believe that is your first try.

Thank you for your comment 2-ton. It is my first try but I didn't make it in 1 day.
It took me a while until I was content with the result and dared to post it

wow, first try? Excellent lion looking face!

About the face a was satisfied. The background could better in my opinion.

Excellent work

Ella, That link was created before I altered the triangulator app to do polygon art all manually, so it's hardcore that you actually did using pure manual method. you might want to try this ->the polygon javascript app<- It helps you produce the same result as manual method but you don't have to Ctrl-X and use color-picker so many times.

Yes i did it all by the manual method. Now i downloaded and installed the file. Thanks tin!

Thanks for the encouragement Marcello

Tran, is there a way to save as I go along? When I make a mistake, I have to start over, and lose a lot of time and effort. Aside from that, I am managing pretty well with your program.
I also wonder if this works on a tablet or if there is a comparable program for my iPad.

if you make a mistake, just click on one of the created point(s) and move it(them) by dragging.
of you can export your partially done art to .svg then combine it in gimp over top of your reference image.
Then continue at a later time by using the combined image, that way you see what you've done in the combined image.

I am still on my polygon art binge, lol. I use the Polygon program that Tin fixed up from Triangulator. This is our big baby Huey of a doggie, Red Dog. It seems easy, but in order to get a really good image, it is not so easy. You have to think about where your polygons are going to make it look good. Mine got a bit jumbled as I was trying to make sure to get the colors right. I think I could have done better to concentrate on the shapes as well as the colors.

I like what you've done a lot 2-ton, it doesn't look easy.
I'm really interested in this kind of stuff, but don't think I have what it takes to create a very convincing piece of polygon art.

nice one 2-ton.
Wallace, it's really easy, it just requires a lot of patience (since it's very repetitive).

I think I'll wait for a plug-in or script.
Maybe G'MIC will come up with something better then what's already available. (Wishful Thinking, with Fingers Crossed)

A script would be pretty cool
but i don't know how a script would be smart enough to pick shapes to make it look like surfaces facing different angles
if such script is possible, then it'll be smart as a script that can turn a 2d image into a 3d model.

This would be a real CHALLENGE to write a script/plug-in.
I don't even know know how the logics would work in order to write such a script.

Don't wast time talking about it, get to work.

GIMP's Mosaic (triangle preset) comes close to making these, but there's now way to control size dynamics where you can choose areas for more details and others with less. If this feature could be implemented, then then solution to automate Triangulator would exist in GIMP.