I'll see if I can find some, would be a shame to buy a whole sepearate cokin-set.
My current cokin (with square nd-filters) fits nicely on my 77 lenses on Canon, as far as I can gather, my Carl Zeiss 80mm F2.8 CF T Planar are smaller in size (not sure what the Mamiya lenses are like though, need to check, once I get the things in the mail).

Good to know there are adapters out there, I like to re-use as much as possible if I can