Powering my Arduino

Hi,
So I have made a Air Pollution Sensor that displays the information on an LCD as well as lighting up some LED lights depending on the pollution level. I need to make a case to cover the project, however I want a button that turns the battery on or off. I have looked everywhere and only found information regarding having a button sitting on a breadboard, however I want the button to be external and on the actual casing. What can I do?
Kind Regards,
Ahmed

There are thousands of push button switches (normally open momentary switches*) that are fastened into a hole drilled in the enclosure.

*Google this term.

Try a weather proof toggle switch - check with your local auto/truck parts store or a marine supply store - I don't do much automotive stuff - but should be a stocking item at marine stores - also try mounting the switch on the bottom of the box out of direct rain

How would I then connect this to the arduino and battery?

groundFungus:
There are thousands of push button switches (normally open momentary switches*) that are fastened into a hole drilled in the enclosure.

*Google this term.

Sorry, I think that I misunderstood your question. If you want a power switch an appropriate one would be a SPST switch (not momentary). There are many to choose from. Wire the normally open terminal (NO) to the + side of the battery and the common (C) side to where the + side of the battery connected before.

The switchs come with a variety of terminal types. I would recommend solder eye terminals for wiring to a PCB wirh flying leads.