Arrange your buttons in a row so that you like the mix of colors and sizes.
Slip the wire through one of the holes of your first button, back to front, and hold the button about 6" from one end of the wire. Feed the working wire through the opposite hole, pulling it taut so that the button “sits” where you’ve placed it. Repeat with the next button, securing it close to the first one. Add more buttons until your string of wired buttons is about 6" long.
Grasp the wire just above the button loop with your round-nose pliers, and make a neat 90° bend there. Adjust the round-nose pliers so they’re gripping to both sides of the wire bend, above and below it. Use flat-nose pliers to pull the wire tail over the end of the round-nose pliers and all the way around, creating a circle with a tail of wire still extending beyond it.
Slip the clasp onto the loop and use flat-nose pliers to hold the circle while gripping the end of the wire tail with round-nose pliers.
Slowly wrap the wire tail around, working from top to bottom, creating a neat coil.
Clip the end of the wire flush with the coil, making sure the sharp tip isn’t sticking out — if it is, use flat-nose pliers to flatten and smooth it into the coil. Repeat on the other side to add the other half of the clasp.