This instructable works for more than one copy ability. You can use it for Sword, Bomb, Sleep, and I think a few others. Here's what you'll need:
-fabric, at least a yard long and as wide as the circumference of your head plus a few inches. Make sure it's the right color!
-More fabric. You don't need as much, but again, it must be at least as long as around your head. It's for the trim. Make sure you make it the correct color. You also need the same fabric for the puffball at the end of the pointy part of the hat.
-Stuffing or cotton balls. It's for the puffball. It' only going to be about three inches in diameter, so it won't be hard to get a good amount.
-A needle or sewing machine, and thread. It's recommended to be the same color as the main fabric, but it doesn't have to.
-OPTIONAL: elastic as long as the circumference of your head
Step 1: Preparing Fabric to Be Sewn
BEFORE you sew the hat into a hat, you have to add the trim. The Take the fabric you have for it and sew it into a sort of tube thing, folding it in half and sewing the ends of the long side together. Make sure that you don't sew the edges yet if you don't have elastic. When you thread the elastic through the "tube," sew the ends, making sure to also sew the elastic. You should stretch it a little, making the hat stretchy and it will fit better. If you don't have elastic, sew it right on the fabric, making sure the trim is on the edge that goes around your head.
When you have the trim ready to go with the elastic, sew it on the hat. At this point, whether or not you have elastic, the fabric is ready to make into a Link hat (with trim and a puffball at the end!)
Step 2: Making the Hat
Now you have to make it into an actual hat! Fold the fabric in half. The trim should be on the bottom edge, on the INSIDE of the fold. If it's not inside-out here, you'll have to start over with sewing the hat together. Cut it into a long triangle shape. Then sew together the edges that you just cut. Now you have a basic Link hat with trim.
Step 3: Puffball! ^_^
Now here comes the fun part! You have to make the puffball, but first, turn your hat right side out, with the trim on the outside and the stitches on the inside. Then try it on. If it fits, good job! If it doesn't, well, I don't know what to tell you. Measure twice, cut once, okay? That works for sewing too. Anyway, take the same kind or at least the same color fabric and draw a circle on it, a little bigger than the diameter of the puffball you want. Double up the fabric and cut out the shape, giving you two circles. Sew it about two thirds or three quarters of the way together, leaving a little opening. Turn the puffball inside out (which is actually right side out), and stuff it with stuffing, cotton balls, or even fabric scraps. If you don't have any of those things, you can always use something that isn't fluffy, but that's kind of a last resort. When you finish stuffing the puffball, sew it closed and onto the pointy part of the hat. Put it on and now you've got an awesome copy ability costume! If it's Sword or Bomb, make a sword out of cardboard or some bombs out of crumpled paper or more puffballs respectively.