This is in the 2nd edition book: Elves of Evermeet. On page 65 there is the description for a spell: Construction.
Casting Time: Special
Area of Effect: Special
Saving Throw: None
The buildings and structures of Evermeet are constructed using this spell. With it, natural materials such as stone, crystal, and wood can be transformed into sculptures, shelters, buildings, or even great palaces.
The building material must maintain contact with the earth at all times and still be in contact at the end of the spell. The material being effected must be within a radius equal to 10 feet times the level of the caster.
The caster can create any object with a volume equal to 1,000 cubic feet (10x10x10 feet) per level. Each 1,000 cubic feet so created takes one entire day. Once created, the object can be added to at the same rate (1,000 cubic feet per day) for as long as the caster wishes.
The DM should work with the player to deter- mine the exact nature of the object or structure created. It can be subdivided with rooms, walls, hallways, or chambers as the caster wishes, but the creation of complex areas such as vaulted ceilings, columns, or galleries will add to the overall construction time. Once construction is complete, the structure is permanent and needs no further magical enhancement or maintenance.
Buildings constructed using this technique will maintain the appearance and texture of the substance they were created from.
These structures are also much stronger than those constructed using non-magical tech- niques. If besieged or attacked, they receive a +5 bonus to all saving throws (DMG, Chapter 9).
I have several questions relating to the spell:
- How much stuff is created in a day? Is it 1000 cubic feet/level, or 1000 cubic/feet? Once constructed, it says you can add 1000 more per day, how does this work?
- How is volume calculated? (I apologize for the math that follows) Imagine you have a house, that’s essentially a cube (30ft side) with a triangular prism on top (=the roof), for which the triangle base is isosceles with a height of 10ft. Let’s say that the walls/roof are 1ft thick. The insides of the cube and prism are empty. That’s about 6x900 cubic feet for the cube’s walls, and 2x541 cubic feet for the prism (we’ll assume the bottom of prism=top of cube). This amounts to about 6500 cubic feet of materials. However, if we take the whole structure, and dip it into a mega-bathtub (à la Archimedes), it would displace 31500 cubic feet. So which volume is correct? One interpretation would take nearly 5x the time to build.
- Casting time? Must you be present and actively participating in the days-long construction process, or can you magically design the whole structure ahead of time, cast it once (in which case, how long is the casting?), and then let it grow according to your vision? Could you use multiple spell slots to build multiple buildings simultaneously?
- Can you re-cast this spell on a building created using this? Since the building is living stone/wood..., and thus an extension of the earth, I would say “yes”. This would allow the creation of large palaces given enough time. (which we know, in canon, happened)
Conclusion: My aim is to decide how long it would take for a single caster (of 20th level) to build a town: comprised of many smaller houses, and a few massive ones. For that I must have answers to a bunch of questions. Can you have multiple constructions going on at once? For building a palace, the archimedes style volume could be huge, so is it only the volume of the materials that counts?