boundingbox

 public static double[] CreateBoundingBox(this ModelDoc2 swModelDoc)
        {
            string value;
            string resolvedvalue;
            double factor = 1000.0;
            var ar = new List<double>();

            var lengtUnit = (swLengthUnit_e)swModelDoc.LengthUnit;
            switch (lengtUnit)
            {
                case swLengthUnit_e.swMM:
                    factor = 1 / 1000.0;
                    break;

                case swLengthUnit_e.swCM:
                    factor = 1 / 100.0;
                    break;

                case swLengthUnit_e.swMETER:
                    factor = 1;
                    break;

                case swLengthUnit_e.swINCHES:
                    factor = 1 / 39.37;
                    break;

                case swLengthUnit_e.swFEET:
                    factor = 1 / 3.281;
                    break;

                case swLengthUnit_e.swFEETINCHES:
                    factor = 1 / 3.281;
                    break;

                case swLengthUnit_e.swUIN:
                case swLengthUnit_e.swANGSTROM:
                case swLengthUnit_e.swNANOMETER:
                case swLengthUnit_e.swMICRON:
                case swLengthUnit_e.swMIL:
                default:
                    throw new NotImplementedException($"Conversion from {lengtUnit.ToString()} to meters not implemented by this method");
            }

            var configurationName = swModelDoc.ConfigurationManager.ActiveConfiguration.Name;

            Feature BoundingBox;
            int longstatus = 0;

            var features = swModelDoc.FeatureManager.GetFeatures(true) as object[];
            var swfeatures = features.Cast<Feature>();
            var bbFeature = swfeatures.FirstOrDefault(x => x.GetTypeName() == "BoundingBox");
            if (bbFeature == null)
            {
                var boolstatus = swModelDoc.SetUserPreferenceToggle((int)swUserPreferenceToggle_e.swViewDispGlobalBBox, true);
                BoundingBox = swModelDoc.FeatureManager.InsertGlobalBoundingBox((int)swGlobalBoundingBoxFitOptions_e.swBoundingBoxType_BestFit, true, false, out longstatus) as Feature;
                boolstatus = swModelDoc.SetUserPreferenceToggle((int)swUserPreferenceToggle_e.swViewDispGlobalBBox, false);
            }

            swModelDoc.Extension.CustomPropertyManager[configurationName].Get2("Total Bounding Box Width", out value, out resolvedvalue);
            ar.Add(double.Parse(resolvedvalue) * factor);

            swModelDoc.Extension.CustomPropertyManager[configurationName].Get2("Total Bounding Box Thickness", out value, out resolvedvalue);
            ar.Add(double.Parse(resolvedvalue) * factor);

            swModelDoc.Extension.CustomPropertyManager[configurationName].Get2("Total Bounding Box Length", out value, out resolvedvalue);
            ar.Add(double.Parse(resolvedvalue) * factor);

            return ar.ToArray();
        }