The Rodscule. The inner and outer rod, Σ′,Σ, (red) are defined by an inner and an outer ellipse, Γ′,Γ, (blue). The 3 points P,Q,R (yellow) define the ellipse and, hence, the Rodscule. M is the barycenter, K
1 and K
2 the centers of the semi-circles of the inner rod, C 1,C 2 the centers of the semi-circles of the outer rod. e
4 and e
4 are the extremal points of the inner and outer ellipse respectively. They define the common points of each ellipse with its corresponding rod, where it is inscribed.