Cut your sweater sleeve into three pieces. Or two if you want to make bigger pumpkins. The pieces can be any size that you would like.
Turn your piece inside out and put a rubber band tightly on each end. Cut a small slit near the seam of the sweater arm.
Turn the piece right side out through that slit you just cut and stuff it until it's full.
Hot glue that seam closed. Yep hot glue. I promise it will work. Then take a needle and embroidery thread and go all the way through the pumpkin through the center.
Keep going around the pumpkin and through the middle about 5 times in 5 different places. Pull tight each time. This makes it look all pumpkin-like. Tie off your thread and I added a bead at the top with hot glue as my stem. You can use anything you like as a stem for your sweater sleeve pumpkins.