OnGui elements as objects?

Apologies if this was already answered somewhere, I didn't seem to be able to find it.

So basically what I'm asking is if someone can direct me in the right way, because I cant seem to find the answer to this one myself.

Long story short, when writing code for gameplay mechanics, you write your class, attach it to a game object, and it is there as a component on that object which I can grab.

In editor scripting however is where I need to change my mindset.

Example, I create my own editor window, in it I can draw some buttons, input fields, etc via OnGui. But, say I create a box Gui.Box(some rect and other parameters). And now I want for that box to have some fields on it, in a way as object has components.

Basically can I declare a gui box within an editor window in a similar way I can declare a GameObject as a variable, and then search trough its components for different values?

A bit raw question I know, all tutorials and documentation I found go trough setting up input fields, buttons, etc in editor window, but this kind of thing I can't find.

Just in case I didn't explain it well, most similar thing to what I'm describing would be a node in a node editor, a "box" with its values as one object from which I can send or grab data when needed.

Again, I don't expect someone typing me a lesson here, I just need a pointer in the right direction, like some kind of "basics" tutorial regarding "instantiating" elements, and since I never tried editor scripting before, if this makes no sense, someone let me know.

Thanks in advance :)