Step 1: Gather Materials
Two matching buttons (although, you could use two different buttons for a mis-matched look). These can be any style of button, they don't have to be 4-hole like the ones shown.
Two lengths of cord, approximately 12 inches each.. I'm using plastic canvas cord, although any cord that will fit through your button openings will work.
I also used a plastic canvas needle to thread my buttons, but if you can manage without one, it isn't necessary.
You'll also need scissors and you may want a ruler if you aren't confident in your ability to eyeball measurements.
Step 2: Threading the Buttons
For four-hole buttons, turn the button so it resembles a plus sign instead of a square. Bring the cord up through one hole and down through the opposite hole. This way, your button will sit centered on the cord instead of off to the side (top of the picture).
For two-hole buttons (not pictured), simply bring the cord up through one hole and down through the other.
For shank buttons, simply thread the cord through the shank on the bottom of the button (bottom of the picture).
Step 3: Tying the Knots
Step 4: Finished and Ready for Use
Caution: Depending upon the cord material you chose, you may need to tighten the knots from time-to-time. You could also use clear nail polish or a drop of hot glue on the knots to hold them in place more securely.