I just hung 6 pictures in a pattern, and I have to say, picture-hanging technology needs to catch up with the rest of the western industrialized world. What you need is to arrange the pictures in the computer, and then using come kind of projector, project spots where the nails go.
And nails are terrible! They leave holes. I’ve tried those hook-and-loop 3M things, but if the weather gets hot, they just dissolve. Useless! Except maybe in New England… with global warming, not even there. It was such a promising technique – they came off sort of cleanly (not perfectly though – I’ve had a couple of them pull paint off), and you could reposition. Also, they show from the side, and are quite obvious. So, terrible.
Somebody, please figure this out. I’d pay for a solution.