Another major principle was to have the ability to create defined combination builds that would utilize every part within their constructions. An example being a Deep Space Glyan that could be configured by using every part of a Hub Set and a Glyan, resulting in an old school Fisher Price astronaut vibe by intention of design.
The larger central parts of the Hub set would also need to function as a PVC/Vinyl connector, allowing for an easy way to change those vinyl female fit functions into female PVC fit functions, opening up some play mechanics.
The above conceptual designs illustrate how the Hub Set and Drone configurations started to really take shape late last year. Being obsessed with classic robots like Robby the Robot, Tomy wind ups (Pocket Bots, Rascal Robots) and small "helper" droids and machines (R2-D2, V.I.N.C.E.N.T., IQ-9) came pouring out and influenced everything about the Hub Set and its combined forms.
Little machines rule.
EDIT: Removed Buxton-mania from the scans!