In order to prove that I really can eke out even the very last shred of use from a pair of thrift store jeans, I made this purse. Only after they were so shredded that I couldn't wear them without facing indecent exposure charges, of course Materials:
One pair of mangled old ratty jeans (don't use new ones for this, you really don't need to!)
Sz 15 knitting needles
Heavy sewing needle
Button - 1" or larger
The first step is to cut the denim into "knit-able" strips. Mine were about 1/2" wide. Thinner or thicker will just alter the gauge, but too thin may disentegrate, and too thick will be impossible to work with. On the parts of your jeans where both sides are still more or less intact, you can start at the bottom and then cut in a spiral. If you run into spots where there's a hole, such as blown-out knees, a zig-zag pattern will yield more unbroken material.
When you get to the very ragged section, cut any of those white strings out to make a flat piece of denim one layer thick:
Then, cut in a pattern like this, starting from alternating directions. Don't get too close to the edge when cutting in, or you'll end up with a lot of little strips. This will give you one long strip, even if it does have some bumpy things along it.
Several times along the way, you'll end up having to start a new piece (particularly to join the strips of the first leg to the second). Just tie the strips together with a square knot and keep the knots to the back of the work while knitting so that you can work the ends in later.
Knit in stockinette stitch for 35 rows or until you run out of "yarn".
Fold the piece in half with the right sides facing and about three inches of overlap on one side. Sew up the sides with your needle and thread, and turn right side out. You should have a pouch with a flap one one side. Sew your button to the short side, and then fold the flap over and button down. I also sewed a pocket to the back, and used the waistband to make a strap. I cut the whole waistband off, then cut the button separate from the rest, and sewed it to one side. That way you can undo the strap and tuck it in the bag if need be. On the other side I just sewed the end into the bag.