Writing lines is a common punishment for naughty children and errant submissives the world over. It’s even used in the opening to one of the world’s most famous TV shows. I saw a twitter post recently where a submissive had done them in a pattern with a different color for every letter, which was pretty neat. However, a user under the handle Stone Mason has taken the idea to a whole new level with these hand engraved slates for Charlotte Douleur. I imagine a selection of lines in engraved stone tablets would make for a great dungeon decoration.

You can see some other images of the slates from the original twitter post.
I believe this is originally from 

You can see a lot more from Elise on her 

I sourced this image from 

I’m afraid I don’t have a source for this image.
You can see the original full size image