Fabric Folding Pen made by Clover
You mix water with a solution (just a few drops required) provided and pour it into the pen which has a foam tip.
Lay your ruler where you want the fold line to be - draw the foam tip along the ruler - finger press. The directions don't say to, but I press with a hot iron to hold the crease. The solution makes the fabric pliable and easy to fold.
It's great to turn under the edges for applique - I don't think it would work on anything except straight lines.
Also great for turning up cuffs, turning under edges for pockets, etc., before sewing.
The directions say not for polyester. I haven't tried it on anything except
100% cotton.NAYY,