I use the tiny capsule, couple of the doughnut shaped fuel tanks and the radial rockets to create tiny crew return vessels. With the new mini lander can a little more weight can be shaved off too. Can probably get away with an RCS tank and thrusters. For real fun I've got a 10 ton SSTO capsule that is just a little too wide to fit in the B9 cargo bay. I have high hopes for the 2.6 engines and radial air intakes to shave off a bit of width. The capsule is capable of ground->orbit->ground flight.