For forms, reports, and modules, you could convert the database to an MDE
file. Just make sure that you keep a copy of the MDB file to make future
changes.

For tables and queries you'll need to implement user level security and all
the fun of that.

You could hide the database window by going to Tools, Startup and
un-checking the database window box. However a smart user would know that
just pressing the F11 key unhides the database window.

You can also hide tables, queries, etc., by putting Usys in front of the
object name as the first 4 characters. Then going to Tools, Options, View,
and ensure that the System objects box in unchecked.