You can design
a huge ship, as a meta-virtual blueprint *
(I.e. it's a ship schematic, which makes it a virtual representation from the perspective of in game rather than a "real physical" ingame version. But the "real, physical" ship in-game is still technically only a virtual ship for us players who are outside the game, hence meta-virtual. And yes, this was a very convoluted and unneccesary tangent, which is why it's a spoiler. In short, Inception much?
but you can't then just plop it down into the game as an actual ship and go to town then and there. As the others have mentioned, there'll be a lot of factors, in particular the need to procure sufficient resources and parts to actually build what you've designed, that will make the construction of a ship take some time. From what I understand/have heard, the planned assembly drydocks will have a more or less set build rate- this means that even if you have all of the mountains of metal and circuitry and other whatnots you'll need for a finished ship, a larger vessel takes proportionally longer to build even with the accelerated build rate of a drydock. So truly jaw-droppingly massive ships will take an age to build, and as mentioned might even exceed the build area of the drydocks that are available in the game.(Excited and inspired spiel coming, skip down to the bottom of the post if you want the TL:DR version)In which case, you'd need to build your ship in sections and then assemble a construction crew to weld them all together properly (or weld it together by yourself),
which would, frankly, be really awesome
if you ask me. (Devs, can you make that happen? Pleeeeease? *puppy eyes*) Not only does it ensure people can't spam Huge-Huge ships, but it also means there's actually extra player time and work/effort beyond just the linear increases involved in making a bigger ship, and follows how such large things/megastructures are/would be/have been made in real life. The International Space Station wasn't drydocked, it was prefabricated as a jigsaw puzzle of modules which were built individually, sent up individually, and then assembled together once they were all in orbit.
The other factor is NPC fabrication. IIRC, the devs have mentioned plans to have generic/default ships which a player can buy from NPCs, with the in-game assumption that these generic and mass produced vessels have already been built (or at least manufactured as a some-assembly-required prefab kit) by the NPC organization you're buying it from. These, you'd be able to pay the appropriate sum of credits/materials for, (possibly more than it would cost to build such a ship yourself- capitalism and all, plus it incentivises player-made ships). However, you wouldn't have to wait for it to be assembled, or if you did it'd be for significantly shorter of a time, because it's been NPC-prebuilt, and so you'd have it very quickly and be able to use it right off.
It's the difference between designing and building a powerful custom car in your garage, and going down to the local car salesman and buying an ordinary sedan you get to drive off the lot. That way, if a player *needs* a ship quickly and is willing to sacrifice the better performance they might be able to get out of a scratch-designed craft (but with a longer wait/build time), they have that option, with its attendant benefits and drawbacks. It also ensures that players who aren't very good at designing ships themselves can still get something out of the game, since if they aren't making headway trying to build something from the ground up, they can settle for buying a stock ship.
Not to mention that the way the game is planned to work, absolutely nothing save time/materials/build requirements is stopping a player who needs a ship NOW but still wants to get good performance out of it rather than just "decent" to buy an NPC-made generic vessel and then tweak the hell out of it with after-market customization.
EDIT: Also, what with the market for those prebuilt ships amongst players who've just started the game, have an urgent need for a new vessel but don't have the time/materials/interest to make it themselves... If there's an extra cost beyond what it costs to fabricate a Generic when you buy from an NPC, this also creates fertile ground for an emergent player-driven market in, amongst other things, those same generic ships. Knowing that cost favors player-made versions, enterprising players could get into the business of building exact "knockoffs" of the generic vessels available from NPCs, and then make a killing selling them to players who Want A Ship Now for a cost that's more than the ship's build cost, but less than the NPC Marked Up cost. Such an arrangement benefits both buyer and seller- The Player 1 seller makes a tidy profit, and the Player 2 buyer saves money buying the ship from them. Price gouging is also impossible because the NPC's marked-up price sets an absolute maximum for player-market price; the builders can't drive up costs like in other MMOs because then nobody would buy from them because they could get it from the NPC shipyards for cheaper.So, to TL:DR summarize:
*Ships in the game will originate from being either NPC made or Player-made.
*NPC ships will intentionally be relatively generic and middle-of-the-road, so that a well-made player-built ship will outperform an equivalent NPC ship in an overall evaluation.
*NPC ships are much quicker to obtain and could be bought purely with cash, but cost more than the raw price of their construction, and as mentioned aren't peak-performance designs.
*Player-made ships only cost the sum of their required materials, but the player has to procure those resources themselves, and player-made ships take more time and effort to build
*Particularly if large ones exceed drydock size constraints and have to be built in sections, then assembled.
*This dynamic enables the natural development of a player-driven economy wherein business minded players build generic ships, which they can sell for less than the NPC manufacturers do, but still turn a profit.
*NPC vendors' set prices enforces that players set fair market prices on their knockoffs.
*The greater supply of NPC-vendor ships and probably sellers vs cheaper player-made copies ensures that NPC vendors are not totally redundant.
*Players who dislike or aren't good at scratch-building ships, or want a ship quickly but don't want it to be mediocre, have a third option; buy an NPC generic or player-copied generic, and then spend the time and resources it takes to soup it up, which is a great middle-of-the-road option.
*Collectively, this covers all the possible routes players could wish from having no ship to getting a ship and having it do what they want, in a way that has reasonable, balanced, and inherent rather than artificially enforced pros and cons to each method.
Edit Zerebo: Split of topic: http://forums.blockaderunnergame.com/index.php?topic=597.0