Sewing is pretty easy to learn, but pattern making is a skill which can take a lifetime to master. Whether you are a beginner or an experienced tailor, making a pattern from scratch is a time consuming and sometimes intimidating endeavor. Rather than spend days making a pattern from scratch, save yourself time and effort by copying clothes you already own!

This is particularly easy with knits and stretch clothing, as fit is forgiving and you don't need 100% accuracy for success. I'm using a cut and sew knit sweater as an example, but any piece of clothing can be copied.

Let me preface that for this project I was going for speed, and therefore did not actually make a paper pattern I can use again. Instead I traced directly onto final fabric and assembled the garment. A little more time spent up front to make a paper pattern would of course save time the next time I did this, but consider this a quick and dirty version of snazzybot's really great Instructable on doing a more precise job of copying a garment, particularly useful if copying a woven garment where accuracy matters.

Ready? Let's go!

Step 1: What You Need

- A garment that fits well to copy. It doesn't have to be an exact copy, you can just copy the part you need (for example the sweater I'm copying is a tunic, but I only am copying the top half).

- Fabric of choice for your new garment, and any findings necessary to complete it (zippers, trim, etc)

- Tailors chalk or a chalk pencil

- Sewing machine/basic sewing supplies

Step 2: Start Copying!

Choose a pattern piece to start with, and begin tracing. I began with the arm.

To start, I carefully laid out the arm of the garment, making sure it was flat and wrinkle free. The sleeve pattern piece will wrap around to the back, so after adding a few pins for support I began tracing along the arm seam, making perpendicular marks at the corners. For the more difficult to trace seam attaching the sleeve to the body, I dotted along the seam by feel. It's hard to be exact for seams that are not exposed, so do your best. Once the whole front of the sleeve was traced, I carefully wrapped the loose fabric around to the back of the sleeve along the fold, and flipped over the whole thing in order to trace the back of the sleeve. How you go about tracing isn't too important in terms of order, as long as the fabric keeps careful contact with the desired panel as accurately as possible. Continue with the same process to trace the back of the sleeve.

At this point, you will have a rough outline of the pattern piece. Use dressmakers curves (or freeform if you are experienced and just know what shape things are) on the whole thing to trace a second smooth line of the pattern, and correct for any obvious irregularities from tracing. Unless you are making a very unique pattern shape, most pattern lines curve smoothly and uniformly, and obvious fit problems can be fixed by looking for odd angles, or wiggles where a line should be straight.

Step 3: Keep Copying

Continue this process for the whole garment. Some pieces are easier to trace than others. The body panels for this sweater were pretty easy to trace, as they are identical at the bottom and only differ at the neckline. The hood was also very easy to trace, as I could trace the entire silhouette when the garment was laid flat, and the bottom of it is a straight line.

Once all of your pieces are smoothed out, cut them out and get ready to sew it together!

Step 4: Assess Your New Pattern

Depending on how stretchy your fabric is, or how accurate you want to be, before sewing everything together it's a good idea to walk your pattern pieces against each other.

This means taking the seams that will meet, and carefully laying them next to each other from top to bottom to see if they are actually the same length. If they aren't, adjust accordingly by either trimming down the piece that is too long, or cutting a new copy of the piece that is too short with the seam in question made longer. Which of these to do will vary in each case, but if in doubt I'll usually lay the pieces against the garment I'm copying to see which seam is more accurate, and use that as a guide for correction.

With stretchy clothing, small differences aren't a big deal. My sleeve ended up being half an inch bigger than the armhole of the body, but I just cut it down and it was fine.

Once you feel good about the pattern pieces, time to assemble!

Step 5: Sew It Together

Now for the easy part, sewing! We have a serger at work which made quick work of sewing my sweater together. This step will obviously vary depending on your garment, so I'll just topline what I did here.

First I sewed the arms to the front and back body panels, then sewed the underarm and side seams. Next I prepped the cuffs with openings for my thumbs, and sewed together the hood along the top, and added a channel around the front for lacing. Last I attached the cuffs and hood, and left a simple serged edge at the hem since the look of the top is already rough.

Step 6: Finishing Touches

The most time consuming part of sewing the sweater together was making the lacing to go through the hood, so I decided to break this out into a separate step. I first made some binding out of scraps, then threaded it through the hood channel with a safety pin. Last I added leather pieces to both ends to keep the lace from pulling out of the hood.