My machine has two horizontal spool holders and an optional third spool that is vertical. There are spool holders that can be off the machine. I've also used a mason jar to hold big spools behind my machine and thread it through the guides and tension. The mason jar worked better on a mechanical than computerized but in a pinch I bet you can get creative. I've seen some really interesting spool holders sold by Nancy's Notions (the artsy ones) and wished I were that creative.