The automatic generation of volumes bounding the intersection of two implicit surfaces (isosurfaces of real functions of 3D point coordinates) or Feature Based Volumes (FBV) is presented. Such FBVs are defined by constructive operations, function normalization and offsetting. By applying various offset operations to the intersection of two surfaces, we can obtain variations in the shape of an FBV. The resulting volume can be used as a boundary for blending operations applied to two corresponding volumes, and also for visualisation of feature curves and the modelling of surface based structures including microstructures. Categories and Subject Descriptors (according to ACM CCS): Computational Geometry and Object Modeling [I.3.5]: Curve, surface, solid, and object representations—