Supplies. Not pictured - alcohol.
Take an old card, like a store loyalty card, and cut 2 sides of a 3/4" triangle with the point facing you. Then cut the third side.
Mark the points for the triangle on the other end. Use the book as a square (not that I'm a little compulsive).
Cut the triangle. Then take your holepuncher and punch a hole about 1/8" to 1/4" in from one triangle.
Like so. You can clean off the pen marks with the alcohol.
Take your emery board and file the points so they're a little smoother and rounded.
Stick the jack through the hole. Then wind the cord around the card inside the triangles.
At the end, pull the buds to one side and mark where they fall. You want them to have a little tension to stay on the card. Punch a hole barely on the edge of the card so it looks like a "u."
And you're good to go. If you mess up with the second hole, you can trim off that side and punch another hole on the other side.