A few years ago together with Lingyun Yu and Petra and Tobias Isenberg we presented CloudLasso, a method for selecting clusters in 3D particle data. We now introduce the CAST methods, novel context-aware algorithms for particle selection. For example, with PointCast one can select a whole particle cluster with a single mouse-click or touch; the algorithm infers an appropriate selection that can then be fine-tuned. For more details, check the paper and video. The paper will be presented at Visweek'15 in Chicago.