The developers will be going into more detail on this at a later date. Founders will have earliest insight into these tools but we won't be able to share that on the regular forums until Stardock opens up about it, but it will probably not be public information until later this year or early next.

However, they have publicly confirmed that ship design and customization will be a big part of the game. It's my unofficial educated guess that it may bear a resemblance to the ship design tools in GalCiv. They are basically developing the game with the same authoring tools that will ultimately be available to players, so it stands to reason the game will be heavily modifiable and we'll have a tremendous amount of design flexibility when designing custom ships.

I asked a few months ago about how designing custom races (a la Spore) would work, and they did reply that this aspect is also being incorporated into the authoring tools, in one form or another. I'm especially interested in seeing how that works; the community will surely come up with some terrific stuff.