sweatshirt jackets are really quite easy- i'd show you a picture of mine but i entered it in the fair saturday-so won't have it back till next weekend-
anyhow- you (de-construct) your sweatshirt (cut off ribbing, neck/cuffs/bottom) cut off sleeves on seams (and open them on inside seam so they are one piece each which will lay flat- cut the side seams so you have a large piece which is the back- mark & cut up the center of the front.
choose your fabrics- i used a variety of width strips from 1" up to 3" wide- sew your fabrics together to create your (strata) making pieces large enough to cover each piece of your sweatshirt pattern with a bit extra- baste & quilt each strata to each piece- then trim around the edges of your pattern- reconstruct along the seams you cut off- then bind the bottom edge, center front, neck & cuffs.
there are lots of sweatshirt jacket patterns on the market.