On Mon, 02 Feb 2015 03:10:59 -0500, Bill wrote:

I do not regard the current cardboard box as a permanent fixture. I
am however open to suggestions. I am thinking about going to hardboard.
Is there something I might glue inside to help absorb fan sounds?

How about hardwood plywood with egg cartons (or that egg carton type gray
foam) over the inside? You could make a nice looking case.