Hi all, Just a quick note, since some of you may be interested. Because yt 3.0 does away with the _grids attribute on data containers, I have implemented something of a workaround for those routines (clump finding, volume rendering) that need 3D data arrays, masks (i.e., _get_cut_mask or _get_point_indices), and possibly even spatial locations from data sources. https://bitbucket.org/yt_analysis/ytep/pull-request/10/adding-a-blocks-attri... -Matt