how do you calculate the volume of a ring
You could thing of a simple ring as being a smal hollow cylinder.
Or an anulus right prism.
Let the outer circle have a radius of R and the inner circle have a radius of r. And let the ring be h units wide.
A=π(R2−r2)units2V=πh(R2−r2)units3
Depends on the cross-sectional shape of the ring. Is it rectangular/circular/elliptical...?