  In this paper we complete the description of the $B\mathbb{Z}
/p$-cellularization of the classifying spaces of all finite groups, for all
primes $p$. The techniques are based in a careful analysis of the $p$-fusion
structure of the groups involved -with special attention to their strongly
closed subgroups- and Chach\'olski's description of the $A$-cellular
approximation.
