I really like it! Very easy and intuitive.

I'd start by adding undo support.

I think next I'd want some way to bring the sections closer together, the gutters feel huge.

And then I'd want some way to drag and drop the sections so I could re-arrange the shapes without having to re-draw everything.

The Chart gallery seems like it could be a more general "placeholder content" gallery. For text, images, chart etc.

Can't wait to see it evolve.

This is a new idea. Wondering where I should take it next. I would appreciate feedback.