Yeah, you can use various industrial switches or you can do it just like this:
I'm using standard small pushbuttons, but I made them waterproof this way. It's two plastic washers that fit together and there's a piece of strong PVC foil (not PE) stuck between them. This assembly of a "drum" is glued around the pushbutton. There is a small hole close to the switch so the air didn't compress when pushing. If I should change the switch (which I hope won't be necessary), I would have to snap this cover off and glue it back again.
Also the foil found in KorrvuŽ packaging is quite helpful. It's highly resilient at all temperatures and easy to glue together. I don't have a clue what it's made of but it seamed to me like some NASA kind of stuff when I first saw it.
Those lever-type micro switches are better to be placed the way the water could't get straight inside. They are quite durable and work well in outdoor conditions, even the smallest ones.