The title (hopefully) is self-explanatory. :) [br][br]For the first screencast, this surface was created by rotating the graph of the function [math]f\left(x\right)=3\cos\left(0.4x+\pi\right)[/math] about the x-axis. Notice how restricting the domain of the surface equation created the fish. (For help constructing the surface equation for this function, [url=https://www.geogebra.org/m/mfdvkbqy#material/kPNmmHgj]click here[/url].) [br][br]For the second screencast, note how using domain restrictions involving absolute value expressions helped create duplicates of surfaces!