I am new to SW and mates. This seems very simple. I want to mate the elliptical cylinder and the elliptical cylinder hole in the block. I would think you could use the face of the cylinder and the face of the block and a coincident mate. Or the ellipse at the top of the cylinder, the ellipse at the bottom, and the corresponding ellipses in the hole in the block.
I tried the Mate function, and Mate References.
A related question is how do you get a point to be visible to use in a mate? Because I also tried using centerlines to specify a centerpoint in each top ellipse, and then could not make them visible to use as mate entities.