Bust of girl with possible Thailand headdress

Hi, I bought this bust two years ago at an estate sale on Sanibel Island.  I don't know much about it except the lady working the sale thought it was made from old shell casings .  It looks like the girl is wearing a headdress from Thailand. The owner of the estate sale was in her late 70's , a world traveler and an avid scuba diver along with her husband who was a Navy man. There is a marking on the back of the neck.  Thank you.