Examples:
The following VBA example creates an ellipse and converts it to a curve shape. It then changes all curve segments to lines, resulting in a diamond shape.
Sub Test()
Dim s As Shape
Set s = ActiveLayer.CreateEllipse2(3, 3, 2, 1)
s.ConvertToCurves
s.Curve.Segments.All.SetType cdrLineSegment
End Sub