Question: Where can I get a latching push button that isn't electrical?

What I want to do or know:

I'm looking for where to purchase (or how to make) a latching push button - meaning, I need to be able to push it in and have it stay in for the "on" setting, and then push it in again to release the tension for the "off" setting. I need it to actually mechanically move, as opposed to just sending signals to a bread board.

Anyone have any ideas? Optimally it'd be something I could buy at a store in Toronto (maybe at an Adafruit supplier like Creatron?) or make from accessible materials.

Background story:

This is for a fun activity with a friend, where we're building a simple light circuit for an art project. The fun part of it is that pushing the button in will complete a copper tape circuit that lights up some lights on a painted UFO... in a yet-to-be-determined space scene.

It clearly isn't for environmental monitoring, but getting this answer might help others who do have this question for a DIY monitoring project (or for others who just want to have fun with circuits).

In the spirit of our "Pompoms" session at Barnraising!

... Sudden realization that I know very little about buttons.