I think you could just take simple measureents and make your own. Here's a suggestion on what I did with Corian:
http://cgim.audiogon.com/i/vs/i/f/1155818602.jpg
Enjoy,
Bob
http://cgim.audiogon.com/i/vs/i/f/1155818602.jpg
Enjoy,
Bob
Vpi plinth blueprint for alternate material?