Easiest way to build a nesting box is this: get an 18 gallon plastic storage tote with lid ($7); looking at the long side of tote, cut a hole in side towards one end. The hole should be the size of a sheet of notebook paper . there should be an inch or so of area left below the hole so bedding...
My dozen gets fed everything. They are excellent garbage grinders. I would steer clear of scratch feed until they are full grown. They get the same stuff in the chick starter. They love cantaloupe !!!!!!!!!!
Pine shavings or clean straw works fine. An 18 gallon storage tub with lid works good for laying box. Cut a hole at one end of the side about 10" wide and 12" high. You can lift lid to get to eggs. This also makes a good brood box for a setting hen and eggs.