Bob, at Gilmore, builds a castle, but it is not available as an add on (as I understand it). Because the shafts lift out, it is angled so they can still come out. I would be very interested to see if anyone has figured out how to do a workaround. If the top of the castle was removable, that seems like it would work. I would love to have a shelf to stash stuff—neither my Gilmore 40” or Fanny 45” have a castle, and there is no possibility with Miss Fanny!