Shells for solids of revolution

These 3d models illustrate the "shell" method of computing volumes of revolution—a typical topic in the calculus sequence.

This model shows the case of the region bounded by x = f(y) = sqrt(3/4-y) + 1, x = g(y) = 1/4 + y, y=0, and y=3/4
f(x) = 3 – 3 (x – 2)², y = g(x) = 0, x = 1, and x = 3 revolved about the y-axis. You can download the solid or the approximation with 10 shells.

I have also included the OpenSCAD file, which is set up so you can modify the functions or parameters to produce your own model.