I love your sorting trays. Good idea. I found some really cool boxes at Sams Club in the meat case that look exactly like nest boxes. It has 3 'nest boxes' in each case. They are really neat so I got two empty ones lol!. I set them out for my new layers (white orps and wyandottes) and they have been using them.
OMG speaking of nest boxes you won't belive this: We had a project a while back constructing one of those large cat house/tree type things that you build from wood and cover with carpet etc. This one has two towers with 3 rooms on one tower side then a large tube connecting them and a tower on the other side with a pagoda house on top. Sooo we never did get the carpet on it haha and it kinda got put on the back burner with all the coop building and other stuff going on. It is in the covered carport attatched to one of the outbuildings kinda forgotten about. Well, the other day I was out there and heard cluck cluck cluck coming from that cat house. I looked over there and there were marans roosters in each of the 3 rooms on the one side and the black birchen marans hen in the pagoda house!! She looked very happy in there and had a bunch of eggs she was hiding lol. Crazy birds!