Toroidal Worlds

Has anyone spent time working on a toroidal (doughnut-shaped) world? I know they would be horribly unstable but I do quite like the idea of it. I intend to work on a world that is a torus, it will have an aspect ratio of 2. It will rotate around its axis of revolution with an axial tilt of roughly 20°. It will have a small moon whose orbit will make it harmonically oscillate up and down the torus' axisbof revolution.