I have made several signs by routing letters into timber, and painting the recessed cut-out a different colour to the timber surface. The letters were about 50 -80mm high, and I used a dome cutter. To get a more accurate letter size and shape I used a PC to print out the text I wanted, in the right sized font, and stuck this to the timber before routing through the paper into the timber. I would now like to repeat this, but using a block of sandstone. I haven't tried, but feel fairly sure my (cheap) router cutter isn't designed for sandstone. Are stone router cutters available? Or do I need something like a mortar raker in an angle grinder? Which I suspect is nowhere near as easy to control as a router. Any other ideas?