When I was using paper on the bottom I used
a Fiskars 193800-1001 Paper Circle cutter. It was ok but I am betting that there are higher quality paper circle cutters available from hobby stores.
to cut
Ahlstrom 6010-1250 Qualitative lab paper
I stopped using paper on the bottom quite some time ago (when I had a Lelit E). Can’t recall why. Might try it again but am guessing that it will give me less body and more clarity in the cup; and I like body.