
To start, I almost always use Warm & White batting, which is pretty flat to begin with. It's important to have straight edges butting together, so if you need to cut fresh edges on your batting scraps, definitely do. Since I always have a bolt of fusible SF101 interfacing on hand, I cut several 1" strips to get me started. Then it's the simple process of laying your scraps on your ironing surface, straight edges together, and ironing a strip of interfacing over the 'seam'. Once you iron on one strip, add on another, slightly overlapping the ends. When you reach the edge of your batting, just trim the strip. Then I like to turn the whole piece over and do the flip side of the seam as well.