A watch spring lies flat on the table. It is made of a coiled steel strip standing a height of 0.3 inches above the table. The inner edge is the spiral $r=0.2 + 0.02\theta$, where $0\leq \theta \leq 4\pi$ (so the spiral makes two complete turns). The outer edge is given by $r = 0.21 + 0.02\theta$. Find the volume of the spring.

volume =