All knotted up

Once in a while, I chance upon 'stuff'. Thing was, I happened to see a Martha Stewart tutorial on this and pinned it, reserving this project for another day. Her project was a floor mat, using rope. I'm thinking the tie-up-the-sailing-boat type, as in thick rope.

Anyway, I found this cord while searching for my beading string. Didn't find the string but remembered the tutorial and decided to make one with the cord. I used another tutorial, by the way, with similar results. Haven't figured out how to tuck in the tails yet.

It took me less than 10 mins to knot this but more than an hour tugging and tugging it so that it'll be a snug fit. For a cord of 0.8cm cross-sectional diameter, I ended up with 10cm x 7cm product. Perhaps a coaster?