Here are all my limit switches for my setup. I only have 1 for the Z direction because I couldn't really find a good way to mount the other Z and didn't have a huge need for it.
Here are the limit switches for the X axis. I mounted these on top of the side walls.
Here are the Y limit switches. I mounted one on the inside of the backside and another on the front next to the stepper motor.
Here is the Z limit switch. I only have one at the top because I wasn't sure where to put another one for the downward Z direction. I don't see a huge need for that unless you don't look at the gcode before you run it. I was thinking maybe in the future that I would add a pressure sensitive bottom that would have a limit to how much force it could take and shut down if it passes a certain threshold. An Arduino would be perfect for something like that and really easy too!