In Microsoft SQL Server 2016 Express Management Studio (July 2016) cannot design a new or existing table.
Image 1: click on the tables node. Where is the menu option
If you uninstall the July edition and re-install the June edition, things will be back to "normal" for you. You do lose the Azure support, however.
Microsoft released a hotfix for this issue already. You can download it here: https://msdn.microsoft.com/en-us/library/mt238290.aspx
This has been reported as a bug:
Microsoft Connect
social.msdn