Abstract: In this paper, we address clustering and collision detection in the clustered shape matching simulation framework for deformable bodies. Our clustering algorithm is "fuzzy," meaning that it gives particles weighted membership in clusters. These weights are a significant extension to the basic clustered shape matching framework as they are used to divide particle mass among the clusters. We explore several weighting schemes and demonstrate that the choice of weighting scheme gives artists additional control over material behavior. Furthermore, by design our clustering algorithm yields spherical clusters, which not only results in sparse weight vectors, but also exceptionally efficient collision geometry. We further enhance this simple collision proxy by intersecting with half-spaces to allow for even better, yet still simple and computationally efficient, collision proxies. The resulting approach is fast, versatile, and simple to implement.