Vinh Vu at Gingko Audio is an excellent craftsman of dust covers. He makes a dust cover for the Nottingham Spacedeck for $249. It is listed on his web site:
www.gingkoaudio.com/prices.html.
The dimensions are listed as 19.5 x 15.75 x 9 inches. If this is not tall enough, he can probably make you a custom version. I recommend his work without reservation.
He is an Audiogon member; his id was "vtvu", but he may have changed it in the last year or so.