Actually, the 'Cylinder into Bathtub' is one of my earlier attempts - my latest 'quest' is the Universal Primitive, a primitive that can transform into any OTHER primitive...

This is my MO-72 Project, a Sphere (72 equatorial divisions by 72 circumpolar divisions) that can change into ALL of the shapes shown here (and then some!). The large spheres on the right show some of the surface polygon groups, while the larger renders in the middle showcase some of the fancier morphs.

NOTE - I had to fake things a bit with the Torus, losing a level of polygons around each of the poles in the conversion - they create a 'disk' that blocks the hole, so I made them 'transparent' for the render. This means that the torus is 72 divisions around the outside rim, but only 34 around the actual thickness of the torus's tube.