most artificer and crafting threads also forget the item crafting rules for large items as well.
stronghold builders guidebook lists the cost of crafting large, bulky, but technically still movable items (statuary, certain monuments, and other non-fixed foundation things) at SL(or PL) x CL(or ML) x 1000, and the cost of crafting immobile items that are a building or are parts of buildings (ie: cannot be moved or removed without destroying the magic and possibly the structure too) at SL(or PL) x CL(or ML) x 500. (note that this "mobility" requirement is completely unrelated to the relative mobility of the stronghold it is embedded into.)
which compared to other methods of crafting permanent items (usually SL x CL x 2000 x duration multiplier in the table) is really cheap. it is 3.0 material though, so ymmv.
my personal favorite use of these rules is to take a folding boat (DMG p249) and noting that it counts as a pinnace (Stormwrack p60) and the sizes listed fall within the volume of 1 stronghold space (SBG p8) and that 1 stronghold space does not strictly have to remain a 20x20x10' shaped volume, but can be a volume of any shape about said dimensions (SBG p8) i can turn the folding boat into my stronghold. a pinnace can cram up to 15 people into 1 ss. i'm pretty sure that assumes sailors on a three rotating shifts for 24 hour coverage of the boat, so not everyone is sleeping at the same time... plus 'other crew', like the party. but see below.
i can expand the internal spaces by using holes of hiding and magnificent mansion or magnificent caravel, and add fun mobility options like flying, submerging, teleporting, planeshifting and so forth. on mine, i paid extra to have two folding masts with lateen sails installed, one on each side so that they can fold out and down for when we're in flying mode, and fold up into the side of the boat otherwise.
have one character snag leadership and pick up a few experts for sailors, another character snag the landlord feat, and we are cooking with grease. get every member of the party to get the landlord feat, and you are cooking with jet fuel.
and speaking of jet fuel, and going fast in general, check this out:
find a plane in your cosmology that has the flowing time trait. use anchor plane, or planar bubble, or a couple of other tricks - on or near the center of your stronghold linked to that plane. if you are using a folding boat, the dimensions of the boat will fall within the radius of most of these effects. everything within the flowing time trait which has now been applied to the area of space-time experiences multiple rounds within the area of effect compared to the rate of the flow of time in the area outside the area of effect... so let's say that the ratio is 10:1, or 10 rounds inside the area of effect compared to 1 round outside. say your stronghold can move at 10 miles per hour... with the time dilation your stronghold is now moving at 100 miles per hour. ^^
if the time dilation ratio is severe enough, you'll find yourself breaking the sound barrier... or maybe even the light speed barrier.... ^^
of course there is that little issue with aging. but, there are a few ways around even that - there's an immortality handbook around here somewhere.
oh, and about that above quote, be sure to check out my master psionics list to find a listing of just about every official power in the entire game. some dms may even let you combine psionic powers in order to meet the effects of a spell - for example: there is no magnificent mansion effect in psionics, but if you use psychoportative shelter (equivalent to rope trick) , psionic unseen servant (yes, there is such a power... or you could use astral construct, i suppose), psionic creation, and psionic fabricate; you've covered all the points of magnificent mansion. or just pay the cost of the spell, plus the npc casting cost for every day of the construction. (if you do the latter, make sure you calc the cost of just adding the spell, to figure out how many days that part of it will take, as opposed to the entire thing all in one go).
