How to order custom platter?

Well, I don't know why you want to change the platter unless you want to go Delrin like The Groovetracer platters for Rega.
Or is the Delrin is already on the Performance DC?
In any Case, for the price with a dimensional drawing Frank can make anything you would like, he does custom work too.

what platter do you want instead? do you want to keep the bearing. If not, you can purchase a VPI Classic alumnium platter or any number of platters from Transrotor, Clearaudio, ebay etc. Otherwise, you can send your bearing to a machine shop and have a custom platter made to fit. Be very careful with packing the ceramic bearing from the performance. Dont ask how I know.

Bacobits1, who is Frank and how could he be contacted?

Manitunc, can you recommend a machine shop?

Many thanks in advance for any contribution,

Frank is from Groovetracer and he does custom work too.
http://www.groovetracer.com/

I havent used one to machine a platter, so I have no recommendation.