Parameters are accessed with C4DAtom::GetParameter()/ C4DAtom::SetParameter(). See page_maxonapi_getting_started_foundations_cinema_parameters.
Parameter: Mode
MDATA_SOLIDIFYTOOL_MODE
Parameter: Thickness
MDATA_SOLIDIFYTOOL_THICKNESS
Parameter: Clamp
MDATA_SOLIDIFYTOOL_THICKNESSCLAMP
Parameter: Position
MDATA_SOLIDIFYTOOL_POSITION
Parameter: Subdivision
MDATA_SOLIDIFYTOOL_BOUNDARYSUBDIVISION
Parameter: Shell
MDATA_SOLIDIFYTOOL_CREATEBOUNDARY
Parameter: Start Cap
MDATA_SOLIDIFYTOOL_CREATEINSIDE
Parameter: End Cap
MDATA_SOLIDIFYTOOL_CREATEOUTSIDE
Parameter: Resolve Intersections
MDATA_SOLIDIFYTOOL_COMPLEX_RESOLVEINTERSECTION
Parameter: Optimize
MDATA_SOLIDIFYTOOL_COMPLEX_WELDCOLLAPSED
Parameter: Perpendicular Boundary
MDATA_SOLIDIFYTOOL_COMPLEX_FORCEPERPENDICULARBOUNDARY
Parameter: Perpendicular Boundary
MDATA_SOLIDIFYTOOL_COMPLEX_PERPENDICULARANGLELIMIT
Parameter: Preserve Corners
MDATA_SOLIDIFYTOOL_COMPLEX_PRESERVECORNERS
Parameter: Preserve Corners
MDATA_SOLIDIFYTOOL_COMPLEX_PRESERVECORNERSANGLE