I recently found the excellent sharpening guide by Friedrich Kollenrott, which according to the link from Dieter Schmid is a reference in the German-speaking world. In it, he talks about making "clinkers" (on page 40), which are bricks with very flat surfaces, using three bricks and some abrasive compound. Has anyone here tried doing this?
I've been using a diamond plate for flattening my fine (1000 grit and finer) waterstones, but I don't want to use the diamond plate on coarser stones because it will prematurely wear out the diamond plate. I don't currently have a good way of flattening coarse stones and I'm wondering if using clinkers is good solution because they can be re-flattened against each other.