Thanks Ken. This is a much better way to cut custom sized segments.
I also want to do some "patio stone" type inside tracks with veneer "grout joints" that would might work best with the trammel point approach, though I could try to make "plates" first, then cut them with Paulick's jig. If the latter (second) method works, it would also be easier. I think I will modify his jig to accommodate larger pieces of shell.
I also saw a jig that used a Dremel with the large cutoff disk set up to make long strips. Larry Robinson mentions the use of a Dremel this way in his book, though he does not go into detail.