public static void AddZAxis(Model3DGroup group, double length = 4, double thickness = 0.1) { MeshGeometry3D mesh = new MeshGeometry3D(); Point3D origin = D3.Origin - D3.XVector(thickness / 2) - D3.YVector(thickness / 2) - D3.ZVector(thickness / 2); mesh.AddBox(origin, D3.XVector(thickness), D3.YVector(thickness), D3.ZVector(length)); group.Children.Add(mesh.MakeModel(Brushes.Blue)); }