How can I limit a user's view to a select group of machines?

QUESTION
I have a user or number of users and you want to restrict their access to only a select number of machines.
How can I limit these user's view to a select group of machines?

ANSWER
This is done via Scopes.
1. Go to the System Tab -> Scopes
2. Create a new scope
3. In the right pane, on the "Machines" page, select the machines that you want the user(s) to have access to
4. In the right pane, on the "Members" page, add the users to the scope.

When the user logs in, they will be limited to the only the machines that you have specified.