If you want to push 2 strands of cord through the hole you will only be able to do this with 3mm cord.
CORD LOCKS SPRING TOGGLES for 2-6mm elastic shock/bungee cord, single/twin hole
Cord Locks Spring Toggles Metal for Elastic Shock Bungee Cord Single Twin Hole
Everlasto 'Lastoflex' Elastic Shock Bungee Cord Rope Black 6mm
10x Cord Ends for Double/Single 3/4mm Shock cord/Bungee/Cord Black Nylon Plastic
Round Elastic cord - stretch bungee cord - 1.5, 2, 3, 4, 5 mm diameter
Round Elastic cord stretch bungee cord - 4 mm diameter
