Gather a few sweaters, cashmere is preferred for its long fibers, but other yarns or fibers will work also. I have used Merino wool, Lambswool, Silk, Alpaca, etc. Clean them (washing machine is fine even for wool, use cold water & regular soap. If it shrinks or felts, that will work to your advantage.) and line dry them.
Step 1: Cut into strips
Cut each sweater into strips. I like to start w/sleeves first. If you have enough time and patience, you can try to cut straight, following the knitting. Since you will be using fusible webbing along the seams later, this is not necessary, although it does look much neater at the end. Most of the time, the sleeve cuffs and neck cuff will not be practical for this project, however, if you save them, they can be made into other products.
Step 2: Make long strips from the short, cut pieces
Connect the strips by sewing the short side together. Usually this requires about 2 to 3 short strips connected at the short ends to make a long enough strip. Make a few (2-3) of these strips to the desired length.
Step 3: Piece together the long strips
Next begin to piece together the strips along the long sides using the zig zag stitch. Now you are beginning to make the top side of your quilt. The bottom edge will be uneven for now, don't worry about that yet.
Step 4: Trim ends
Trim off the ends evenly along the top and bottom. You can do this each time a new strip is added, or when all the strips have been connected.
Step 5: Strengthen seams
Now, strengthen the seams with fusible webbing. You can buy this material in craft stores. Follow the instructions of how to iron on the product. This should be done along the backside of all the long seams in order to sew it with a machine. It is unecessary if you are hand quilting.
Step 6: Add backing
Attach a backing material (I prefer cotton gauze) to the patchwork piece. Sew the sweater strips onto the backing along the long seams again. In other words, along the long sides of the sweater strips are 2 stitches. Place the sweater piece on top of the backing, with the sweater side up. If you fused the seams together already, no pinning or basting is needed. Just use the zig zag stitch along the same long seams again, reenforcing those seams. These edges should be able to withstand use and wash now that they have been stitched twice and fused, too.
Step 7: Finish edges
Bind the sides with the method of your liking. You can bind it like a traditional blanket, I chose to run the perimeter in a serger with contrasting thread for a nice effect.
Step 8: Final presentation
Finished! Steam the blanket for the best presentation.