7:40 PM, Thursday September 2nd 2021
If you mean a cylinder that has ends that are ovals/ellipses in a specific fashion (like with particular proportions), then your best bet would be to start by building a box that fit those proportions and then constructing ellipses in its ends. If you're just talking about a cylinder that has been smushed down in any fashion, then that's more a matter of context.
That is to say, if we try to place a cylinder in the context of a scene (a regular, circular-end cylinder) then we have to work pretty hard to make sure those ends do represent circles in 3D space, when compared to all the other vanishing points/factors in the scene. If we don't, then it's likely that our cylinder is going to be more squashed, with ellipsoid ends.