I need to write this down here before it evaporates into thin air. Engeström's complex structure of activity has proved to be extremely helpful in my research, but the more I work with it the more I find that its one-dimensional and linear nature doesn't quite capture what goes on in real life. I'm working on a three-dimensional version of it, adding one more element which I think is fundamentally missing, and would like to replace the arrows with channels where energy flows freely, just like blood in the heart.
Just an idea. I know it might be crazy, but I need to explore it just to have some peace of mind that I didn't let it go unnoticed.