I have a puck of backing paper, free for the cost of shipping. OD is about 85mm. Paper in good condition, most of then still have the "exposed" sticky tape.
Just send me a private message with your PAYPAL account name -- and the postage cost -- or you can send me a PAYPAL invoice to ******* {Moderator's note - please do not include private, non-commercial email addresses in publicly visible posts. The scamming miscreants are out there!
The Private Conversation function is perfect for the purpose}