Creating a carbon fiber structure with tongue and groove joints?

[Mongo]

I am looking for a way to create a lightweight, load bearing structure using flat panels that have been cut with a CNC.  Then, join these panels together in a more tongue and groove / wood joinery type method.  Is this possible?  I assume it will not be as rigid as a structure built out of a mold, but how much will I be losing?   

[AJ Sawyer]

That's an awesome composite structure! Mortise and tenon or tongue and groove. It's used a lot for optical benches and reaction structures. It's plenty stiff and strong. It just has to be designed properly to transfer loads

https://markets.rockwestcomposites.com/aerospace-defense/structures/case-study-reaction-structure/

[Jeremy Senne]

It's worth noting that you should also use some sort of epoxy or other adhesive as a fillet bond along the corner joints to keep the structure together.

If you really want to go all-out you could bond angle clips between the adjacent faces for the strongest structure of that construct.  That's how a lot of satellite structures are built.