In some examples, a system includes a plurality of posts and a plurality of cage panels, wherein each of the cage panels is removably coupled to one or more of the plurality of posts, wherein a nominal width of each of the cage panels is congruent based on a modulus, wherein an actual width of each of the cage panels is equal to a difference between the nominal width of the cage panel and the width of one of the plurality of posts, and wherein any combination of a subset of the plurality of cage panels coupled in a common orientation to a subset of the plurality of posts has a combined width, between respective centers of end posts of the subset of the plurality of posts, that is congruent based on the modulus.