2.5D Head Rig !!!

[striker2311]

Hello everyone,
This 2.5D head is awesome, you definitely wanna check it out.

Link - https://www.youtube.com/watch?v=MueURT_ ... l=Toonmilk

Though I've gotta question that for correction bones at time stamp - 1:00:13. he only could have done that because he had already planned out in beginning about its dimensions and lowered all the layers by that proportion and he also didn't changed shape of eyes (for head moving up and down) . So, because of that he was able to do what he did.

But, What if there was a random face with no set dimensions and eyes shapes was also changed while moving up and down. Then how can I achieve this?