The Prescribed Density feature () can be added from the model tree under Component>Definitions using the Topology Optimization context menu. Any Density Model will have the selection of its filtered, projected, and penalized variables extended (or overwritten) by the Fixed Topology Domain selection. If the Density Model uses Helmholtz filtering, the filter will be extended and use 0, 1 or θfix as input to the filter, depending on the Fixed value setting.

From the Fixed value list, choose User-defined, Void or Material. The Void and Material options corresponds to the Prescribed Void and Prescribed Material features, respectively, while the User-defined option allows setting an arbitrary value, θfix, to be used in place of the control variable.