You can make potholders! Any shape, square would be easiest. I chose to make a heart.
Wool, cotton, or a blend of the two works best.
Here is what you will need:
Insulating material - I simply used a double layer of a cotton t-shirt
Template material - I used a file folder and drew half a heart free hand at the folded edge
1. Decide what size and shape you are making and make a template.
Use your template to cut the following:
1 front panel - place it anywhere on the sweater
1 - 2 layers of insulating material, your choice
2 back panels - for the back panels, lay your template's halfway point along the finished edge of the waist band. See 4th photo.
2. Sew the insulating layer(s) to the front panel, wrong sides together.
3. Sew the back panels to the front panel, right sides together.
Trim off the extra material to prevent too much bulk. (Of course, if you own a serger/overlock this isn't necessary.)
4. Turn the potholder right side out.
5. Sew around the entire shape with about a 1/2 inch seam.