One of the reasons I haven't published a blog post yet on the nodes, even though they are pretty much done. Is because I didn't finish the design yet. Well, earlier today I finished the design. Reinforced it in some locations, and included options to stack them.
The stacking will have to be designed. But finalizing the design is already a big milestone. Designs will be available (for sale) on Bricklink and/or ReBrickable at some point.