The O-ring cord (if it is soft and durable enough) will work just fine. In a previous place of employment we had a kit that could be used to make custom o-ring of most any size - it consisted of:
1) various diameters of o-ring cord
2) a simple device with channels in it for each diameter of cord and a slot through which a razor blade would fit - this allowed one to easily make nice perpendicular cuts on the cord
3) Some "super glue - like" glue to glue the ends together and
4) a jig that would keep the ends aligned while gluing.
I beleive the kit was from Parker O-rings. BTW - it is also possible to get the cord in a design that is flat on two sides. A good source for O-ring parts (and for all kinds of other hardware) is McMaster Carr. Go to their web site (
www.mcmastercarr.com) and do a search on o-rings - a lot of good information on types of cord stock, hardness, material type etc will come back as will links to products. Scroll down and you'll see links to their o-ring splicing kits. You can also view and price these by going directly to their catalog pages - page 3238 of thier courrent catalog has the splice kits listed. The "inch kit" in silicone "includes four 7-ft. long pieces of cord stock in diameters of 0.103", 0.139", 0.210", and 0.275" (unless noted)", goes for $46.67 and includes a simple jig and glue.
I might also point out that McMaster Carr is also great source for other hardware including stuff made from stainless.
Roger on the SeaDNA