Finally, at the end of the course, we discuss the Poincaré universe as modeled by the interior of a circle in the Möbius plane (as described in the demo). Note that the formulas, etc. on which the demo is based will already have been derived as part of the previous sections of the course. Note also that the demo is a prototype, i.e. it was designed for use in the course, but was not actually used (for technical reasons, and because it is incomplete).