Octothreads

One of the trends in caps is raised "3D" lettering. It's made by sewing over foam. The thread can't press down the foam, and the needle perforates the edge just like paper towel, and when you're done sewing it pulls away from the hat. Here's a time lapse of the process. It doesn't show up in the video- but there is a special tool used to hold the foam down while the machine starts sewing. It's not a good idea to put your hand near the sewing area of an industrial machine.