That's a widget that has been around forever. If you live in Seattle and want one they have them at Hardwick's in the case to the right of the pliers and probably at Seattle Fabrics too. If I'm hand sewing I prefer to use a sailmaker's palm and needle but it's a good tool if you haven't learned traditional hand sewing skills.
"Just to be clear, doing the Diamond Knot requires at the minimum double IPAs to be DIR." - MattleyCrue
"Mmmm....... Oreos!
They didn't look too good when I was spitting in my mask for dive #2!" - cardiver