Well, I did a little searching and found info on David Massingill which included this bit:

Massengill plays a mountain dulcimer created by Edsel Martin, a master whose dulcimers, famed for their extra long bodies and beautiful carvings, are displayed in the Smithsonian. He went on to a tell a long story about Martin and the Liars' Club, which led directly to his song in tribute of Martin, "The Whittlin' Boy."

Still looking for direct info on Martin.

Thanks