Wood if I could

I'm reminded of that scene in "Apollo 13" when the engineers had to solve the carbon dioxide build-up in the ship. They had to literally put a square block in a round hole with only what they had on hand. My challenge is far less critical to survival, but I still had to think about it.

The rounded back of the chin needs to be attached to the flat surface of the woodblock using what I have on hand. (Otherwise, hello Amazon.com). 

I settled on using Magic Sculpt epoxy to create a flat surface on the back of the chin. First I roughed-up the backside of the chin so the Magic-Sculpt would adhere. Then I put chunks of the epoxy on both sides of the chin interior and pressed it against the flat woodblock to create a flat surface on the epoxy. After the Magic-Sculpt dries, I'll attach the chin to the woodblock with crazy glue.