I believe the best way, although not the most flexible, of creating "buildable" vehicles is to use the method that makes the current player model possible; hiding parts of the shape (nodes) based on user selection. This won't lead to truly open construction of mobile creations, but it would allow players to customize their vehicles with whatever parts the original creator decided to put in them. You assign different properties to certain configurations to make things more interesting (more powerful engines could mean a fast vehicle for instance).
To sum it, you wouldn't be placing individual bricks to "build" your vehicle, but would rather be choosing from a selection of existing designs. Not the most exciting kind of construction, but it would certainly be more efficient and less error-prone than trying to move various DTS shapes around in concert (remember the avatar items in V0002?).
