Эквивалент вашей разметки будет следующим:
HelixToolkit.Wpf.TubeVisual3D pipeVisual = new HelixToolkit.Wpf.TubeVisual3D();
BindingOperations.SetBinding(pipeVisual, HelixToolkit.Wpf.ExtrudedVisual3D.PathProperty, new Binding("Pipe.Path"));
BindingOperations.SetBinding(pipeVisual, HelixToolkit.Wpf.ExtrudedVisual3D.TextureCoordinatesProperty, new Binding("Pipe.TextureCoordinates"));
BindingOperations.SetBinding(pipeVisual, HelixToolkit.Wpf.TubeVisual3D.DiameterProperty, new Binding("Value") { Source = PipeDiamSlider });
BindingOperations.SetBinding(pipeVisual, HelixToolkit.Wpf.MeshElement3D.MaterialProperty, new Binding("Pipe.Material"));
BindingOperations.SetBinding(pipeVisual, HelixToolkit.Wpf.MeshElement3D.BackMaterialProperty, new Binding("Pipe.Material"));
pipeVisual.ThetaDiv = 50;
pipeVisual.IsPathClosed = false;
BindingOperations.SetBinding(pipeVisual, HelixToolkit.Wpf.MeshElement3D.VisibleProperty, new Binding("IsChecked") { Source = PipeIsVisibleCheck });