I didn't have very good luck last year when I tried a queen introduction with a push-in cage on my topbar hive. The bees managed to chew away the wax and kill the queen. So I built this based on one I had seen for a Lang hive. It's 10" long and 6" deep. (it could be shorter if I wasn't making it do double duty as a queen bank). The lower screened portion is where you would cage the queen for a few days until she was accepted. The blue push pins are how you get her in the cage. The white marshmallow is how the bees release her (or you could use a cork if you are going for a brood break in your hive).
The 8 hair-roller cages up top would be used to hatch/store mature queen cells/virgins until they can be introduced into a queenless nuc. The shelf would also work for regular queen cages that come with packages so that you don't get wonky comb built around a queen cage that is hanging from a wire.