40d:How do I increase the value of a room

Wall and Floor quality

Material

Digging a room within a layer consisting of obsidian or flux will inherently give it a higher value than a room built inside a mundane stone such as granite or gabbro. Additionally, veins or clusters of precious minerals (whether ores or gems) which pass through the room can provide a dramatic boost in value.

Engraving

Room quality can be increased by smoothing and engraving the walls and the floor. Stone can be smoothed by any skilled dwarf without decreasing quality, but always engrave with more skillful Dwarves as unskilled Dwarves will permanently prevent you from putting a nice engraving there.

Construction

Constructing floors in a room using high-value building components (such as aluminum or platinum bars, or perhaps soap made from megabeast fat) can dramatically increase the value of a room if its location is important but valuable stones do not occur in the region. Note that constructed floors cannot be engraved, and constructing a floor on top of an existing engraving will destroy the engraving, resulting in the usual consequences of art defacement.

Furniture

Lever

Levers count as furniture for the purpose of increasing room value, and an unlimited number of mechanisms can be connected to a lever simply by linking it to an object and subsequently deconstructing said object (either directly, or by simply pulling the lever if the object is a cage, restraint, or support).

Trap

Weapons not being used by your dwarves (whether due to your military structure or due to the weapon being inherently unusable) can be placed in weapon traps, and traps located in a room will increase the value of the room by the value of all components. A trap containing an artifact weapon can easily max out a room's quality. This works for both conventional weapon traps and upright spears. As an added bonus, a strategically placed menacing spike in an annoying Noble's room can also be employed for the purpose of arranging an unfortunate accident.

Cages

Cages seem to add the value of the animals occupying them to the room value, and you can store unlimited amounts of animals in one cage.

Other items

Coffins not set to burial are not considered rooms and so can be built in other rooms without decreasing that room's value. This takes up space, but you do have to put the coffins somewhere anyways. You might as well get value from them.