At this point, I had just enough wood left for the lid (I did not buy extra beams, so it's a good thing I did not make any mistakes while cutting the wood).
The perimeter of the lid is all 2"x2" beam, and the center beam is 1"x2". Cut two (2) 4' beams (i.e. cut a 2"x2"x8' beam in half). Cut two (2) 21" beams from 2"x2" beam and one (1) 21" beam from 1"x2" beam.
Assemble the pieces to form an "8" shape.
Cover the top of the lid with chicken wire. Pull the wire tight as it will tend to stretch anyway, and will bulge if it is too loose.