Do I understand this correctly that you need to safely store your random grid since only the pattern is in your head? Losing the grid would then essentially mean you can't access your keys anymore even though someone else also can't. But maybe I overlooked something. Will take another look tomorrow.

However, I want to mention the technique of making up a story to remember the seed words. I found this to be fairly easy so I am not sure how this grid can be more useful than that.

But still a very cool and interesting idea! Thanks for sharing. (You even made me create a HN account to post my first comment)