Parameters are accessed with C4DAtom::GetParameter()/ C4DAtom::SetParameter(). See Parameter IDs.
Parameter: Mode
MDATA_SOLIDIFYTOOL_MODEParameter: Thickness
MDATA_SOLIDIFYTOOL_THICKNESSParameter: Clamp
MDATA_SOLIDIFYTOOL_THICKNESSCLAMPParameter: Position
MDATA_SOLIDIFYTOOL_POSITIONParameter: Subdivision
MDATA_SOLIDIFYTOOL_BOUNDARYSUBDIVISIONParameter: Shell
MDATA_SOLIDIFYTOOL_CREATEBOUNDARYParameter: Start Cap
MDATA_SOLIDIFYTOOL_CREATEINSIDEParameter: End Cap
MDATA_SOLIDIFYTOOL_CREATEOUTSIDEParameter: Resolve Intersections
MDATA_SOLIDIFYTOOL_COMPLEX_RESOLVEINTERSECTIONParameter: Optimize
MDATA_SOLIDIFYTOOL_COMPLEX_WELDCOLLAPSEDParameter: Perpendicular Boundary
MDATA_SOLIDIFYTOOL_COMPLEX_FORCEPERPENDICULARBOUNDARYParameter: Perpendicular Boundary
MDATA_SOLIDIFYTOOL_COMPLEX_PERPENDICULARANGLELIMITParameter: Preserve Corners
MDATA_SOLIDIFYTOOL_COMPLEX_PRESERVECORNERSParameter: Preserve Corners
MDATA_SOLIDIFYTOOL_COMPLEX_PRESERVECORNERSANGLE