If you want it extra warm, take a 1/4 yard of fabric(fleece is best), and **cut it into 2 pieces(cut so you have 2 shorter pieces, not skinnier pieces) and place them on top of eachother.** Fold them in half hamburger style sew up the sides, leaving the top open.(the bottom is the fold.) Then fold the top down, (so the raw edge is outside,) down about 1/4 inch(and pin) Sew it all the way around. Not together, like the sides, but by sliding the bag onto the machine, like a sock, so the needle will hit where you folded it and sew it, until you hit where you started. if you need it less warm, only use 1 of those pieces, where i put the **'s
Is that clear?? Depending on you particular fabric, it may be wider, or vise versa, so this may not work. If you have any questions, or if this is too confusing, just let me know!!