I learned today that if you sculpt an item and you want to reuse it, that you can rotate but not scale in -x to flip it. Because the normals will be flipped. When you apply the scale all your previous brushes will be inverted. So dents become bumps. Scratches are now lines that lay on top of the flat. And where the scrape brush was used there are now hills.
Also I learned that those nice premade brushes that you can download are set up to also appear on the backside of your object, but inside out. Of course you can turn on Front faces only, but I didn’t know that.
Something else that didn’t go as planned is that i applied the mirror too soon and had to delete those duplicate objects.