You can choose any weight of yarn that you want. A fine yarn is closest to the thickness of hair and will lay more naturally, but you will need more of it to complete the project. On the other hand, you could use a bulky yarn and simply unwind the strands once the hair piece is sewn into place. It’s completely up to you.
To adapt this process for a boy doll, simply make several wefts using shorter yarn. Attach them to the doll’s head in horizontal rows, beginning in the front and adding more close together until you reach the nape of the neck. If desired, you can lay the hair flat and glue it to the head of the doll. Or you might consider doing this with a few strands in the front, so that the doll has a fixed hairline. Just use a white craft glue that will be flexible when dry.
The glue will ultimately give a specific shape to the fabric, since it dries in the shape of the doll’s head. It also provides some stiffness, to secure the cap in place when you’re done.
At this point, you should have something that looks almost like a shuttlecock from a game of badminton. One end will be rounded and stiff, approximating the shape of the doll’s head, while the excess fabric will trail out around it.
The cap should look roughly like a snug-fitting sock that is molded to the shape of the doll’s head.
Don’t worry too much if the ends of the wefts look a bit unfinished. You can arrange the hair so that it falls over the ends to conceal them.
