To be fair, they also made a number of fixes and improvements in the base code itself and like good Free Software citizens, contributed them back to the project. Those contributions are in the current 1.0RC2 release of FreeCAD. I think they were wanting to try the same play that launched RedHat back in the day. I appreciate their contributions and I'm sorry it didn't work out for them.

I've been experimenting with that sort of thing. I've been experimenting with a slicer and g-code hacks to do inlays and other simple multi-color prints with just one swap per color. It looks like at least some printers could manage OP's print OK. One of my tests was a jack-o-lantern.

I had good results with CC3D green using a steel 0.4mm nozzle.

The first was when I was 5. A friend and I were tossing huge (well, huge to a 5 year old, probably not that big) rocks over a railing that was nearly as tall as we were. One hit the railing and came back on my head. Looked at in the ER, turned out to be no big deal.

I mostly remember that because the ER was nearly empty and we were seen without waiting. My how times have changed. Also because they were testing the generators and I thought it was cool the way the whole floor was vibrating.

When I was 7, going down a slide, a long stick hit the ground first and jabbed me just above my eye. My first stitches. I still have a nearly invisible scar from that.

It may be worth going a little hotter. I do 245° (250° if a steel nozzle) and 5° hotter for the first layer. Part cooling no more than 20% except for bridging. I dry it it 60° with plenty of hot air flow.

I got really good results with CC3D GID PETG and a steel nozzle.