After the bottom cabinet was roughly assembled, my wood shop teacher and I began running dados (similar specs to the bottom) for the top cabinet. These first dados went much smoother than the bottom and we were able to fit them with ease. After this we began running dados a quarter inch in from the edge of all the sides, top and bottom of the top cabinet. We ran them at 1/4” so we could fit the plywood backing in that we ripped to specifications after fitting and re-measuring the top cabinet. Assembly of the top cabinet and gluing was a painstaking process due to the tightness of the fit for the backing. We had to preform slight rips on the backing to achieve the desired fits and were (finally) able to glue this bastard together.
-- "Nothing is over until we say it's over! Was it over when the Germans bombed Pearl Harbor?!"