For this project I used an old pair of jeans. The jeans fit me perfectly but they were full of holes and I was going to throw them away. They were perfect for cutting apart to draft a new pattern. Below are the steps I used.
1. First I cut jeans apart along the seams. I only cut one side of the jeans apart because both sides are almost the same.
2. Then I laid the pieces out as flat as I could on pattern paper. The paper I use for this is just leftovers from a large commercial printer. I can't believe they were just going to throw all that good paper away. Large pieces of newsprint paper also work well for this but you might have to tape a few pieces together. Pattern tracing paper, with the 1" blue grid printed on it, also works really well but it costs more than the other two options.
3. Next I carefully traced around all the pieces with a pencil. I think I wound up with about eleven different pieces. After each piece had been traced I set the jean parts aside.
4. I added labels to each piece so that I would be able to tell what they are and how many to cut. I also added grain lines.
5. Each piece that I traced needed to be cleaned up so I used my 3"x18" ruler and french curves to make sure that my lines were strait and smooth. I also checked to make sure that all my pieces would match up when they are sewn together.
6. Then it was time to add seam allowances. I used a 1/2" seam allowance because it is just easier than using the traditional 5/8". For all the straight lines I used my 3"x18" ruler again. For all the curved lines a compass works wonders. Just open the compass up to your desired seam allowance and then trace around any curve.
7. The last step to drafting the pattern was adding markings for things like pockets.
The back pockets you see on my jeans are actually from another pair and not the originals. That's one of the cool things about drafting your own pattern. You can add or change any details you want. If you are at all unsure about your drafting skills be sure to make a muslin first so that you can work out all the "kinks" first. Otherwise, just jump right in and start making your new jeans.