It depends on the item. Small pieces will either tack base or spray glue. Lap quilt upwards either pins,( those expensive curved safety pins not the lower priced ones) or spray glue. The method also depends where I am doing the sandwiching. My friend doesn't allow spray glue in her classroom area. I must admit I love using the pins and removing every time I go past one. So liberating when you see a few pins left. If I use glue I always wash before I give it away to remove the glue.