Here I offer you a tool that is simply attached to a second toolbar by means of a clamp. Suitable for toolbars up to 12mm in diameter.
The mount for the laser has a diameter of 20mm and takes all common lasers with a diameter of 10-20mm.
Whether wired or with batteries, everything is possible.

Simply throw a laser line on the stone and you have a perfect guide to always sharpen curved knives cleanly in one line.

The lasers shown are not included and are for illustrative purposes only.