Dropdown nesting boxes?

So saw a video and in the video the rabbit cages wire made had a drop down nest box built in were the doe can drop down into a smaller box wire made to nest in place of wooden boxes. Any one have any experience with this? I just bought two new wooden boxes instead of building them but now wondering if this is a better option. I may create another cage later and try this but as of now I have the cages already built and boxes purchase but I like the idea of a built in nesting box that could just be covered with a piece of board until needed. Of course this isn't possible for stackable cages.