Threadkilla,
They make queens castles and they also make small queen mating nucs. They are about half the size of a regular nucs.
I am trying queen castles, this way I can just move regular size deep frames around as needed. And, it only takes 2 frames
to get her mated. Don't have to fill a 5 frame nuc until you know she makes it back.
There is also plans on the forum for making 4 complete nucs, including tops, out of one sheet of 4x8 plywood. makes them really economical.