This outside corner scriber for use in forming outside corners on sheet vinyl, but works ok on rubber, and vinyl base. It scribes a line on the side of the corner that needs to be cut, using the opposite  side as a guide. The guide leg has a rounded end for following the contour without scratching. The guide leg is adjustable in relation to the needle  for various material thicknesses, and is held in place by a knurled steel fastener. The needle height is also adjustable for various material thicknesses.

Needles Available HERE