For what purpose does Papa use the family garage in the novel, The Year of Billy Miller?

The garage at the Miller household is where Papa works on his found-object sculptures, rather than where the cars are parked. The garage is full of all kinds of found objects, from silver garden balls to cigar boxes to cellos, as well as various sculptures Papa has made. The garage is also where Papa goes to work on his new art form, assemblages, in the middle of the novel.