I’m not so sure this nyctograph is that good of an idea.
Problem number one is remember which cells you’ve already written in; problem number two is to remember which pages you’ve already written on.
I do a lot of my writing in shorthand which works fine in the dark except for that second problem, how to turn to an unwritten page.
I mean these days, since there are electric lamps, there’s no need to use actual fire to see in the dark which was more of a schlep.
If I’m sure I’m on an unwritten page (maybe by folding corners?) the shorthand solution works great. Perfectly readable the next morning.
That nyctograph also remind me of the Braille template and stylus I use for writing Braille letters and signage. That’s how I discovered problem number one; I haven’t used a nyctograph but the Braille template also has rectangular cells. I’ve messed up when using that Braille writer by accidentally skipping cells which meant accidentally introducing extra spaces in the middle of words. Or it could mean doubling down and overwriting letters but that hasn’t happened yet.