I have not make an apple core quilt, however I have made a drunkers path. You should not need to clip any seams. You really don't want to clip because it will weaken your seams. Yes this is a quilt that is better done by hand, however it will come out well with a few things. I woudl suggest that you use sizing or starch (I use sizing, it is available in the market). Spray your fabric until wet and let dry until almost dry and iron dry. If you are doing this by hand, get a piece of fine grain sand paper and draw around your pattern with a pencil. I use macanical. Trim your fabric to a 1/4 seam allowance, but it doesn't have to be perfect. Place a pin in the corner and then thru the corner of the piece you are joining. Match center and other corner. Continue putting pin thru your seam line and match with seam line or ajoining piece. Check to see that you are sewing on the line. If you are doing this by machine, you still have to pin unless you have a Curve Master presser foot. It really is cool. You also have to start and stop at each corner like you would in a Y seam. Also a lot of seam will help when you are done.