Can I put an Airport Extreme in client mode (sharing printer only)? I have an Airport Extreme 3rd gen (A1301). I just bought a Time Capsule 5th gen (A1470). I put the TC where the AE used to be, in a cupboard in the hall. Now I am thinking to repurpose the AE as a printer server on my desk. 

Can I configure it so it connects to the wifi of the Time Capsule in client mode? I don't want to extend the network of the TC since then I would risk connecting to the Airport Express instead of the TC with my other devices, which would be undesirable.
On a Windows version of Airport Utility ctrl-click on the "wireless mode" menu will give you an additional option "join a wireless network".  Without ctrl the option is hidden.