We will not change the part. The part is dual mold and to use it it has its surfaces modeled as it.
However you need to outplay Partsdesigner.
Why PD does not project on the complete surface is a riddle, the surfaces are actually four subfiles and it projects only onto two.
Nevertheless, I tried to apply serveral decals onto 68881 and I discovered that you can trick it to apply the decal on the other surfaces as well.
So I cut off a "Mouth only" section that is 10 x 2 studs from the original 10x5 studs image
I then positioned and applied the mouth first
Once that was OK, I applied the complete decal:
After that it looks ok like this with the complete Face:
My picture did not have an transparent part, that's why you till see the border.
However you need to outplay Partsdesigner.
Why PD does not project on the complete surface is a riddle, the surfaces are actually four subfiles and it projects only onto two.
Nevertheless, I tried to apply serveral decals onto 68881 and I discovered that you can trick it to apply the decal on the other surfaces as well.
So I cut off a "Mouth only" section that is 10 x 2 studs from the original 10x5 studs image
I then positioned and applied the mouth first
Once that was OK, I applied the complete decal:
After that it looks ok like this with the complete Face:
My picture did not have an transparent part, that's why you till see the border.