When our neighbors moved away, they gave us a nice metal nest box with plastic bottom liners. We built this box into the new house, with access doors on the back.
This box is positioned quite strategically. First, we have it positioned on an outside wall so that we can easily collect eggs. Second, the height is such that it is lower than the lowest roost. This is to make it an undesirable place to roost (sleep, that is) for the girls. Notice that it isn’t on the ground though. We wanted for the chickens to have access under the box, so that they can keep that area free of bugs, snakes, and other undesirables. You can also see in the second nest box picture above that there are two access doors. This is so that we can more easily control any birds that might be in the nest box when we are collecting. A smaller opening is easier to block than one as large as the whole nest box back.