Hey, If you have been to our Users Meeting 2013 in Berlin in the mid of October you have seen my presentation: Intersecting surface in parametric models: Subsurface modeling. The presentation will be available on our website within the next days. http://www.friendship-systems.com/downloads/presentations This is the live demo project file. It is sorted with multiple numbered scopes. This sorting is helping you to understand the order of creation and makes it easier to reuse it in your own projects. Subsurface: It is the trimming/cutting functionality in CAESES-FFW.Creates a new surface on the basis of an existing parent surface.CAESES-FFW provides some Feature Definitions which will help you creating subsurfaces. Here you can find them: Menu -> Features -> Surfaces -> subsurface or in the CAD Menu next to the object Sub Surface If you have any questions to subsurface modeling please don't hesitate to post them here or contact me. Best regards Karsten UM2013_SubsurfaceModeling.fdb