Here is a 2 state button latch that I made. It has 2 states as in the name the up state and the down state.

To put together you just slide the button piece(the one with the spring) into the guide piece and then put the pin into the guide and the slot on the button. This way the pin catches on the slot in the button in two spots to create the two states. The model is not perfect and sometimes it can go the wrong way but just wait or re adjust it and it will work again. I plan on making a much better model but I was proud of this and wanted to share.