I doubt they'd offer a pattern, but if you are looking for the proper dimensions of a Roman chasuble, stole, maniple, etc., I recommend calling or e-mailing someone at Gamarelli or Barbiconi in Rome. They still produce the vestments properly (according to the Roman style), and they could probably give you the dimensions to which someone could either make or adapt a pattern. For example, many "Roman" chasubles made today and in the past (especially in France, Spain, above all in America) do not fit the proper criteria. They have the cross shape on the back rather than the pillar. The chasuble is not wide enough or is cut straight or looks like a fiddle (hence the "fiddleback" title, which really is proper to the Spanish style in particular), etc., etc. N.B. A proper Roman chalice veil has no cross, neither do the bottoms of the maniple or stole (only the part that is kissed at the top), though these last two examples in particular were increasingly popular.