Outside cover. Sewing through 4 layers of foam with walking foot and going slow is so not an easy task. When I got to the section that had other layers inside my machine just would no longer cooperate and the stitches started to go around the layers and deform. I so wish I could have sewed the binding with a straight perfect stitch, but foam is unforgiving. The holes would tell the story even if I pulled the stitches out.
I guess I just have to say this adds character.