As I mentioned, I modify breeder boxes. We breed our birds in rectangular cages. I cut an opening at the top of the cage for the box to slide down for placement in the cage. I attach some thin plywood to two sides of the box to close the gap between the top of the breeder box and the top of the cage. If you buy breeder boxes wholesale, they are pretty cheap. Lately, I have applied wood glue to the seams and applied several coats of polyurethane to them. Reason being, if you try to clean out a breeder box with liquid solution, it will not get completely clean and it will most likely fall apart on you since the box manufacturer merely staples it together. The glue helps keep it together and the polyurethane will seal the wood so that it can be properly disinfected. I have come across some articles on use and disposition of breeder boxes. I have recently heard that a wooden breeder box should only be used for one clutch since it cannot be adequately disinfected for follow-on use. I feel that if you buy a breeder box and seal it with polyurethane , you are in better shape. There is no telling what bacteria, virus, or hazardous chemicals may have gotten onto the wood and/or breeder box in its processing. I disinfect our polyurethane sealed breeder boxes after each clutch is to the handfeeding stage and reuse it for the next clutch with no problems. Polyurethane is not harmful in the cured state. It forms a very thin layer on the wood and if the bird was to ingest it, it would pass through his system. It is no more harmful than those plastic toys you buy for your birds they totally distroy in a couple of months.
I have tested both a newly purchased and one of my reused polyurethane boxes for bacteria. Neither box produced any growth on agar plates. I ran the test as follows for each box: