Future demands on TCAD frameworks and simulators will include even more three-dimensional simulation capabilities. A precondition for this is the effective manipulation of three-dimensional geometries. While the PIF interchange format and the PAI procedural interface are already well-prepared for three-dimensional geometric data, a strong need for geometry manipulation and editing arises with the upcome of simulators capable of handling three geometric dimensions. A G3S library similar to the G2S two-dimensional geometry library is necessary to provide those capabilities for the VISTA framework.