If you feel uncomfortable wearing leggings or tights, buy a pair of sweatpants or linen pants with a skinny fit. You can also wear green cut-off shorts if you don’t want to wear long pants.
Make sure that you or whoever the costume is for tries on the shirt before you purchase it. The tunic is an iconic part of the Peter Pan costume, so a short or tight shirt won’t look as good. You can buy a regular T-shirt or polo shirt, or a shirt made from linen or another similar material for a more earthy feel.
If you are happy with the size of the shirt, make the zig-zag pattern close to the edge of the fabric. If you feel the shirt is too big, draw the zig-zag higher up, so that you will be able to cut the shirt to the length that you want. Also draw a V along the neck of the shirt if it’s not already a V-neck.
If you don’t want to sew, you can do a no-sew version of the cap by simply taking a green beanie and flipping up the edges. Glue a red feather to one side of the beanie to create a perfectly good Peter Pan cap!
To estimate what size the triangle should be, hold the cloth up to your head to get a good idea. Since the hat isn’t going to be fitted snugly to your head, you just need to get an approximate estimate.
You are sewing along what will be the inside of the hat, so don’t worry if your stitches aren’t perfect.
Don’t use a real knife. Even if you want to pull off a great costume, it’s not worth the risk of accidentally poking yourself! You can also make a dagger out of cardboard and paint it to look like a knife.