Elijah bought earrings to give to his mother for her birthday. The earrings are in a case shaped like a rectangular prism that is 2 inches long, 1 1/2 inches wide, and 1 1/2 inches tall. He doesn't want his mother to guess what the gift is, so he put the case in a larger, cube-shaped gift box. The gift box is 4 inches along each edge.
What is the volume of the extra space left in the gift box?
