Here's how I dissect a pair of jeans...
#1. Cut the inseam from the bottom edge of one leg, up to the crotch, then down the other side to the other leg’s bottom edge.
#2. Next cut the front from the crotch up, along the zipper, almost up to the waistband. Then go across, and around the pocket, and down the side seam - just long enough to get past the pocket on the inside.
#3. Then, cut across the back, just below the pocket, and down the back seam.
#4. Repeat for the other side, and you have 2 denim “pelts.”
1. Building Your Denim Stash: If you have 3 boys, like I do, you are likely to have a bunch of their old jeans, with holes in the knees, lying around. These are a perfect way to get started. Also ask your friends and neighbors and relatives to send you their old, worn out jeans. The next best thing is to shop the yard sales or flea markets. I won’t pay more than 50¢ a pair, and will be able to find about 12 pairs of jeans on an average Saturday. If you’re looking for a particular type of jeans, or are willing to pay higher prices, then check the thrift stores. Know the difference between denim and chambray. Chambray looks and feels like denim, but is too thin to be denim. Also, try to avoid “stretch denims.” They have lycra or spandex in them which may become warped and unattractive with use.
2. Color Values: Denim comes in so many shades of blue, and lots of other different colors, too. Just like regular quilts, you should work with light colors and dark colors and medium colors, to give your quilt depth and interest. Collect a good variety.
3. Cutting Denim: I like to use my rotary cutter. Denim is very thick and will give your poor fingers blisters if you cut with scissors. And, even if you are using a rotary cutter, your wrist may become sore. So pace yourself. Cut up 1-3 pairs of jeans per day. Or cut up a couple in the morning and a couple more that evening. Never try to do it all in one day, you may injure your hand, arm or shoulder.
4. Sewing Equipment: Some machines come with a "denim foot," which is helpful because it has a straight-stitch hole, which helps to stabilize your fabric as you sew. But, if you have a walking foot, use that instead, because it helps feed the layers of fabric through evenly. You will need a bigger sewing machine needle. Use a “universal,” “sharp,” or “denim needle” in a size 90 or 100. Use good quality thread. I use "Metler Silk-finish," color #789. I would also recommend using quilter’s pins. They are longer and have a bigger head, and work better with thick fabrics like denim. However, NEVER sew over a big pin in denim! It may damage your machine.
5. Another handy thing to use is a "seam jack" or “jeans jack.” This is used to help your machine sew over bulky, doubled-up seams. You can buy a little plastic tool that was designed specifically for this purpose. Or make your own with some folded cardboard. The idea behind this is to keep your presser foot horizontal, by putting something of the same thickness under the front or back of the foot as it is going over the extra bulky area. I've got a tutorial on how to use a seam jack on my other blog. "How to Use a Seam Jack"