private FabricSheet CreateCustomFabricSheet(Document document, Element wall)
{
    if (FabricSheet.IsValidHost(wall) == false)
        return null;

    // Create a new type for custom FabricSheet
    ElementId fabricSheetTypeId = FabricSheetType.CreateDefaultFabricSheetType(document);
    FabricSheetType fst = document.GetElement(fabricSheetTypeId) as FabricSheetType;

    // Create some fabric wire types
    ElementId idWireType1 = FabricWireType.CreateDefaultFabricWireType(document);
    FabricWireType wireType1 = document.GetElement(idWireType1) as FabricWireType;
    wireType1.WireDiameter = 3.5/12.0;

    ElementId idWireType2 = FabricWireType.CreateDefaultFabricWireType(document);
    FabricWireType wireType2 = document.GetElement(idWireType1) as FabricWireType;
    wireType2.WireDiameter = 2.0/12.0;

    // Create the wires for the custom pattern
    IList<FabricWireItem> majorWires = new List<FabricWireItem>();
    IList<FabricWireItem> minorWires = new List<FabricWireItem>();
    FabricWireItem item = FabricWireItem.Create(2.0/12.0, 1, idWireType1);
    majorWires.Add(item);
    majorWires.Add(item);
    item = FabricWireItem.Create(1.5 / 12.0, 10.0 / 12.0, idWireType2);
    majorWires.Add(item);

    item = FabricWireItem.Create(3.0 / 12.0, 1, idWireType2);
    minorWires.Add(item);
    item = FabricWireItem.Create(3.0 / 12.0, 10.0 / 12.0, idWireType2);
    minorWires.Add(item);

    fst.SetLayoutAsCustomPattern(6.0 / 12.0, 2.0 / 12.0, 4.0 / 12.0, 1.0 / 12.0, minorWires, majorWires);

    FabricSheet sheet = FabricSheet.Create(document, wall, fabricSheetTypeId);
    // Regeneration is required before setting any property to object that was created in the same transaction.
    document.Regenerate();


    AnalyticalModelSurface ams = wall.GetAnalyticalModel() as AnalyticalModelSurface;
    sheet.PlaceInHost(wall, ams.GetLocalCoordinateSystem());

    // Give the user some information
    TaskDialog.Show("Revit", string.Format("Flat Fabric Sheet ID='{0}' created successfully.", sheet.Id.IntegerValue));

    return sheet;
}

Private Function CreateCustomFabricSheet(document As Document, wall As Element) As FabricSheet
    If FabricSheet.IsValidHost(wall) = False Then
        Return Nothing
    End If

    ' Create a new type for custom FabricSheet
    Dim fabricSheetTypeId As ElementId = FabricSheetType.CreateDefaultFabricSheetType(document)
    Dim fst As FabricSheetType = TryCast(document.GetElement(fabricSheetTypeId), FabricSheetType)

    ' Create some fabric wire types
    Dim idWireType1 As ElementId = FabricWireType.CreateDefaultFabricWireType(document)
    Dim wireType1 As FabricWireType = TryCast(document.GetElement(idWireType1), FabricWireType)
    wireType1.WireDiameter = 3.5 / 12.0

    Dim idWireType2 As ElementId = FabricWireType.CreateDefaultFabricWireType(document)
    Dim wireType2 As FabricWireType = TryCast(document.GetElement(idWireType1), FabricWireType)
    wireType2.WireDiameter = 2.0 / 12.0

    ' Create the wires for the custom pattern
    Dim majorWires As IList(Of FabricWireItem) = New List(Of FabricWireItem)()
    Dim minorWires As IList(Of FabricWireItem) = New List(Of FabricWireItem)()
    Dim item As FabricWireItem = FabricWireItem.Create(2.0 / 12.0, 1, idWireType1)
    majorWires.Add(item)
    majorWires.Add(item)
    item = FabricWireItem.Create(1.5 / 12.0, 10.0 / 12.0, idWireType2)
    majorWires.Add(item)

    item = FabricWireItem.Create(3.0 / 12.0, 1, idWireType2)
    minorWires.Add(item)
    item = FabricWireItem.Create(3.0 / 12.0, 10.0 / 12.0, idWireType2)
    minorWires.Add(item)

    fst.SetLayoutAsCustomPattern(6.0 / 12.0, 2.0 / 12.0, 4.0 / 12.0, 1.0 / 12.0, minorWires, majorWires)

    Dim sheet As FabricSheet = FabricSheet.Create(document, wall, fabricSheetTypeId)
    ' Regeneration is required before setting any property to object that was created in the same transaction.
    document.Regenerate()


    Dim ams As AnalyticalModelSurface = TryCast(wall.GetAnalyticalModel(), AnalyticalModelSurface)
    sheet.PlaceInHost(wall, ams.GetLocalCoordinateSystem())

    ' Give the user some information
    TaskDialog.Show("Revit", String.Format("Flat Fabric Sheet ID='{0}' created successfully.", sheet.Id.IntegerValue))

    Return sheet
End Function