As your "eyes" are the same than the other side maybe you can try to erase than copy past...

But better is refound how you have build all these for avoid that the next time! :)

impossible to solve without rebuilding the boolean diff parts on top of the head

so i rebuild the part to obtain a solid to boolean diff ( construction lines on the 3dm file )

now the head is solid without this constellation of small segments

same problem for the mouth ... select border ... join extrude and boolean diff ok

maybe it could be useful to do an incremental save

project 1.1 ... 1.2 etc

sometimes it's easier to find where is a problem ... your's I never see that

maybe there is a script to do that ... in 3dsmax or other softs it's VERY useful and recommended ;)

Hi Simon, I've attached a tuned up version that is all solids now. I needed to untrim and then retrim those misbehaving areas.

Did some parts of this object happen to be initially created at a much different scale level than other pieces?

- Michael

Thank you chaps for looking int this and apologies for creating such a nightmare model.

I actually built it a couple of months ago but I dont recall that I did any wild scaling (although I guess its possible I 'could' have changed the modelling units mid build and done something but I cant confirm)

TBH I'm not that interested in finishing this model as it was just a little concept test but mainly interested in the technique that you use to fix it. (I hope it didn't eat too much of anyone's time.)

Now I know that I will need to look at untrim/trim in future. (Join/separate is normally my goto fixing method). Thanks Micheal for the solution!!

A big thank you to everyone who took the time to look at this.

Simon