Years ago when I worked in a shoe plant sewing those stripes on those old black and white track shoes, my machine had an endless bobbin like that for all six seams. So, I had 12 spools of thread to deal with. It was great! I could sew and sew and sew. When I ran out of a spool, I'd just tie on another spool and pull it through and go again. Maybe they will come up with one if they haven't already. I'm sure going to find out when I buy mine.