Hide SQL database from Management Studio
1. Create a user account (make sure its not mapped to any Database)
2. Right Click on the upper section of the SQL (SQLSERVER Name)>Properties>Permissions>Click on the user account, and select Deny to view databases.
3. Right Click on the newly created DB, Properties,Files, and change the Owner to the newly created account.
At this point, once the user logs in he will see the Master,tempdb and will also see the new DB which he is a DB Owner of..
You may want to go to Tools>Option and enabled the option to hide system objects so that you don’t show the master,tempdb,etc.
You may also need SP1 if this option does not work