They come across Ebay all the time. Meissner made one, as did a lot of other companies. Go for the big round one, rather than the little oval kind.
Mine is custom made by a friend who was working in a motor rewind shop at the time (a long time ago).
The one referenced in this thread
http://audiokarma.org/forums/showthread.php?t=85071
looks just like the old ones (pretty much) , but for 50 bucks... I'll bet you can do a lot better on Ebay.
John