How to make an illusory mansion?

[redking]

Let's say an NPC had a threadbare mansion. The mansion is structurally sound, but nothing is in it. Also let's say that that the NPC is an illusionist with little money to furnish it.

How would an illusionist go about turning a threadbare mansion into an illusory mini palace worthy of the wealthiest person in the realm? What spells would be of use in this situation?

[Jack_Simth]

Let's say an NPC had a threadbare mansion. The mansion is structurally sound, but nothing is in it. Also let's say that that the NPC is an illusionist with little money to furnish it.

How would an illusionist go about turning a threadbare mansion into an illusory mini palace worthy of the wealthiest person in the realm? What spells would be of use in this situation?
(Extended) Mirage Arcana (https://www.d20srd.org/srd/spells/mirageArcana.htm) can do the entire thing if you're OK with having to renew it regularly.

For a Permanent solution:
Illusory Wall (https://www.d20srd.org/srd/spells/illusoryWall.htm) is the big one. Costs just the slot, and is Permanent out of the gate. It's limited to 1 foot thick, but walls, ceilings, floors, and decorations on the same (tapestries, climbing and flowering vines, carvings, murals, et cetera) are all covered with this. A lenient DM will let you layer it a bit to get bigger objects (ten illusions at one foot thick by ten feet tall and ten feet wide each, all adjacent to each other, to make a ten-foot cube statue kind of thing), but a stringent DM won't.

Permanent Image (https://www.d20srd.org/srd/spells/permanentImage.htm) if you can skip (or afford) components for the big ticket items - furniture, statues, and so on.

Doors are problematic, unfortunately.

Edit:
If you want to be crafty, you illusion up the outside via Illusory Wall (https://www.d20srd.org/srd/spells/illusoryWall.htm), and then make the door line up with a Mage's Magnificent Mansion (https://www.d20srd.org/srd/spells/magesMagnificentMansion.htm). The inside is real (for a while, at least), but elsewhere. The key component isn't illusion, though, unless you're talking Shades (http://www.d20srd.org/srd/spells/shades.htm), but a caster with 9ths isn't poor for long.

[Duke of Urrel]

The best way to handle illusory doors is to create illusory servants to open them, so that your guests don't have to touch the doors at all. Illusory servants (created with the Major Image spell) can be used to interact with everything that looks solid but is really insubstantial. Maybe you can even add "Do Not Touch" signs to keep visitors from touching the furnishings and art objects in the mansion that aren't really there.

You can also hire a few real servants to handle all situations that require close contact with guests. These servants can take your guests' cloaks and hats, direct them to sit in the few chairs that are real at the few tables that are real, and serve them real food and drink. These servants can be allies of yours disguised with the Disguise Self spell or the Seeming spell.

With the Mirage Arcana spell, you can make any building look bigger on the outside than it is on the inside, because you can make whole walls and ceilings invisible. (Whereas figments limit you to adding things to spaces, glamors allow you to seemingly subtract things from them.) You just have to make sure that your guests aren't allowed to wander about. You need to confine them to the spaces that are actually real spaces, so that they don't bump into any invisible walls or poke their hands through any insubstantial doors.

[Particle_Man]

A large number of illusory walls a few feet in from the real walls even gives you built in secret passages.

[Silva Stormrage]

Pixies have permeant image as an SLA so no material component cost. Recruiting some pixies with the promise of being able to stay around in the mansion if necessary or binding them via Spirit Binding (Via a Runestaff or some other way to get it on their spell list or just via hiring a Wu Jen) and get them to spam out Permanent Image everywhere. That is probably the best option for all the static illusions needed.

Also just because they want everything illusionary you still want mundane things as well. An illusionary throne is less impressive if you fall through it when sitting down. A block of stone or wood that feels like a throne due to illusions is much more convincing.

[Jack_Simth]

The best way to handle illusory doors is to create illusory servants to open them, so that your guests don't have to touch the doors at all. Illusory servants (created with the Major Image spell) can be used to interact with everything that looks solid but is really insubstantial.The problem with Major image is that it requires concentration. Sonorous Hum can bypass that... for one illusion only, and for it's duration of minutes/level (although it is eligible for Persistent Spell). If you want to have more than one moving door, you'll need more than one Major Image, and that presents an issue.

[MornShine]

You're probably just looking for this (pathfinder, but official pathfinder):

https://www.aonprd.com/SpellDisplay.aspx?ItemName=Hallucinatory%20Decor

[Segev]

Consider magnificent mansion, with the door overlapping with the front door of your mirage arcana mansion, or just the façade put up by your permanent illusory walls.