[youtube https://www.youtube.com/watch?v=_dQJBBklpQQ]
The beads are the type you get on office blinds. A larger version of the beads you get on dog tags.
Slow mo video and explanation here:
Search for metal 4.5mm bead chain on ebay to get the same as these. You can buy several short chains and link them together. The same search will bring up the links too.