LL_RC mm "RC (Radius of central hole)" LL_ZCO mm "ZCO (Distance from bend to bottom of central hole)" LL_RO mm "RO (Radius of outer holes)" LL_YOO mm "YOO (Distance from edge to outer hole)" LL_ZOO mm "ZOO (Distance from bend to bottom of outer hole)" opt.obj1 kg "Bracket mass"