Magnetic Seam Guides have been available for a generation or so, but this one is just for sewers. You can even use as Fridge Magnets!
Choose from Sewing Machine, Tape Measure or Zipper.
Attaches magnetically to your sewing machine’s needle throat plate
Allows uniform seam width acting as a guide for straight stitching
Anti-skid design prevents magnet from sliding around
Lightweight, rust-free plastic construction