Here is the melted top of the head figure mentioned in the previous post:
same print slightly different light angle to bring out different details
In the meantime I got a somewhat better result (just printing top of head since the rest of the model prints fine and I don't want to waste time and plastic). Some settings:
Ultimaker Original
print in PLA
Layer height: 0.25mm (I'll do 0.1 or 0.15 for final version after fixing issues, but for sake of speed in testing, 0.25)
Wall thickness: 0.6mm (nozzle diameter)
Spiralize
Smooth Spiralized Contours
Speed 90mm/sec.
Temp: 214°C
Adaptive max. variation: 0.27mm
Adaptive step size: 0.03mm
Adaptive layer threshold: 200
It's almost usuable, at least there's no hole. I'm not sure what to tweak next to get rid of the peaks and valleys. Maybe reduce extruder temp at that z-height.
Below was the first attempt, for reference. Just spiralize, no adaptive layer height. I think the layer height was 0.15mm and the overall height 120mm, that hole about 30x38mm.