Approximately five to ten cubic yards of soil are required to construct a single chamber mound, ten to fifteen yards for a double chamber mound. If your site has good drainage, the chamber and connecting pipes may be laid out on the ground surface and then dirt carefully piled on top of them. If drainage may be a problem, build the mound first, then dig trenches for the chamber and pipes. This will ensure that the chamber is above existing grade. Nest chambers may be constructed of concrete or plastic irrigation valve boxes obtainable at landscape supply, home supply, and many general hardware stores.
Concrete material is preferable as it provides the greatest thermal protection.
Ideally, the inside dimensions of the chamber should be between 1,200 and 1,750 cubic inches of floor space. Mark or sketch the chamber location so that you can locate the buried lid in the future, if the need should arise. This is important, as this configuration will minimize light inside the nesting chamber. Two pipes are necessary to allow proper ventilation and escape routes should a predator enter the chamber. Pipes greater than four inches allow easy entry for potential nest predators and should not be used.