Holy cow, now I seen everything.
This looks like friggin plastic coil we use to spiral bind books with! The more I look, the more I think that is exactly what it is.
I would have to see one in person to be sure, but you can go to office max or Kinkos, or just about any copy shop, and buy this stuff in sizes ranging from 6mm to 50mm diameter in 2mm increments, in 12-15" or 36-40" lengths, in a variety of colors, for a few cents a piece. The most common sizes being 10-24mm, and most common colors stocked are black, white, red, blue. But it comes in just about every color you can imagine, even clear.
Man, we have thousands and thousands of pieces of this stuff in stock on the shelf at work in just about any color you can imagine, and we pay about 5 cents a piece for it, I could make a killing selling this stuff!