Update: I wasn't happy with tying a knot in the cord for the necklace. Since the back of the piece is not shown in the movie, I took a little artistic liberty in making it so it could be taken from its display (in progress) to wearing it without too much effort. I also wanted to stay "true" to the piece, meaning, since it is basically authentic (read: no modern materials in its construction (minus the drops of glue)), I didn't want to use some kind of store-bought clasp, which would have snatched it from the hyborian age & dropped it squarely into the 21st century. So this is what I came up with:
I took two 3/4" pieces of brass tubing and aged them overnight in ammonia fumes. Then I made a loop in one end of the cord & bound it tight with some very narrow twine. This made it thick enough so that one piece of the brass tubing was immobile (unless forced).
On the other side, I ran the cord through the loop, folded it down into an opposing loop, & slid the other piece of brass tubing up to secure it. It worked out just right.
In other news, this is the first time I used the ammonia brass-aging technique, & I have an FYI for anyone thinking about using this aging process. Keep an eye on your brass once it's spent some time in the ammonia fumes. Only leave it in for as long as it takes to darken it to your liking.
I put the brass in right after dinner (around 7:30 P.M. that night), & left it until I got home from work the next day (around 5:00 P.M.). When I took the pieces out, one of them had COMPLETELY cracked (all the way through) down the entire length of the tube. Luckily I was able to put an ultra-thin bead of epoxy on the break & fix it so that it's virtually undetectable unless closely scrutinized.
Anyway, "voila".