Trisphericon

The trisphericon or (3,1)-polysphericon is the simplest polysphericon. It has a single developable face, but, as will any odd polysphericon, it cannot roll and thus isn't a developable roller. It can be made by bisecting a cone with apex angle $$\pi/3$$ through it's apex and rotating one of the halves by $$2\pi/3$$.