Attribute Error in Marionette Posted January 10, 2017 Thanks for all your comments. @Alan WoodwellI see the same problem with the "get list length" node. It will start to return zero after a few times running the network. I did put this down to my own noob wiring but maybe you are on to something there. What I am doing is I am sorting the books and then shuffling them inside their sorted blocks so I don't get very wide books stacking on top of very narrow books. At the same time, the stacks don't look totally neat. As I mentioned before, my next step would be to fix the distance between leaning books and stacks. Still a bit of work remaining but I'm loving it. Placing the books manually would have been hours of very dull, repetitive work.