If you don't have or don't want to spend about $200 on an industrial button machine, contact an upholstery shop to make fabric-covered buttons for you. Use regular buttons, or purchase button kits from a craft store. Follow the manufacturer's instructions for making the buttons. This headboard has 130, size-30 buttons. Button size is primarily based on your preference.
When all of the buttons are made, string one end of a 20"-long piece of button twine through the loop on the back of the button. Then string both ends of twine through the eye of the button needle.