Clover Hera Marker
I use this small Hera marker to mark small quilts with lines that do not need to be removed. It dents the fabric, it doesn't make a permanent line to erase. I've also used it to help poke out the points on my Tiny Dresden plates.
It's also suited for marking and creasing on appliqué or reverse appliqué. There are many uses for it in appliqué & sewing.