Question about 120 scanner masks for CS8000 and 9000

Hello,

Would anyone who uses either of the medium-format glass holders with their

Coolscan 8000 or 9000, be able to describe the newton ring prevention masks

that come with the holder?

I bought a used Coolscan 8000ED and the glass medium format carrier (the non-

rotating one) but I did not receive the masks.

I know that I could probably replacement masks from Nikon, but I was hoping

that I could make them myself.

Are they simply a thin sheet of paper or plastic designed to prevent contact of

the film with the upper glass, or is there more to it than that?

Thank you kindly for your help.

Jeff