What does Billy's father do for a living in the novel, The Year of Billy Miller?

Papa is a stay-at-home dad, but is not a typical stay-at-home parent. He works from home as an artist, though he has yet to have his breakthrough. Papa works in found-object sculptures, but is not getting along very well. The work is not speaking to him. Papa helps Billy with his bat cave diorama for school, and when Sal dumps glitter in Billy’s diorama, Papa uses a hairdryer to blow most of it out –and tells Billy that real rocks can sparkle. Billy suggests Papa make dioramas as art, and Papa decides to give it a try, going one step further and making assemblages. They are a hit, and his career begins to take off.