When Seth speaks of CUs we tend to think along the same lines, as if our entity is like a rigid, hierarchical, well-defined molecular construction. I don't think that is the case. I suspect that the concept of CU's only makes sense to beings like us who are immersed in dimensional spaces, particularly in duality ... where we see separation and boundaries between what we think of as identities within a field of oneness.
The best I can come up with as a potential metaphor is the idea that consciousness is like an infinite dimensional abstract mathematical space. CU's in that hypothetical construct would simply represent a set of basis vectors. Like any set of basis vectors, it would "span" All That Is but it would not be uniquely defined. By that I mean the following. If you look at our simple 3D space, there are an infinite number of potential basis vector sets. They differ by where they origin is located, by their orientation, and by their shape (e.g. we're used to linear systems, but there are things like spherical coordinates, cylindrical coordinates, etc.). "We" at any moment of action (in some plane of action, such as Earth) could be viewed as a vector process (function) in that space ... which could be projected as "components" along that infinite set of CU's. Hence it would be reasonable to say that the Inner Self is formed of CU's ... and to note that this set is not uniquely defined but rather is very specific to your perception.
Have fun with this ... maybe you can comer up with something better!
“Basically, there are no real divisions to the self, but for the sake of explanation we must speak of them in those terms. First of all, you had the inner self, the creative dreaming self – composed, again, of units of consciousness, awareized energy that forms your identity, and that formed the identities of the earliest earth inhabitants. These inner selves formed their own dream bodies about them, as previously explained, but the dream bodies did not have to have physical reactions. They were free of gravity and space, and of time.”
(Dreams, “Evolution” and Value Fulfillment, Session 894)