The .NET controls do not appear in the Toolbox after selecting to add them to the Toolbox.

If you right click Toolbox and Choose to Add Items and select the OPCWPFDashboard controls, yet they do not appear in the Toolbox you may have installed Visual Studio after Open Automation Software.  If so uninstall Open Automation Software and reinstall it.  It will then register correctly with Visual Studio for adding the controls.