Odd-numbers (comes to a 1x1 point) pyramid.
ASSUME: A "tomb" consists of a floor with a coffin on it. to conserve materials, no walls are used, each level of the pyramid is simply filled with coffins.
ASSUME: This pyramid will be beautifully smooth-sided. What's the point otherwise? (its also easier to build, but takes more materials)
NOTE: as "level" goes up, we're actually going down the pyramid. Level 1 is the top point (a single upward ramp)
NOTE: Total rose gold used assumes that all constructions (and the door or doors on the bottom level) are rose gold. With furniture assumes the tombs are rose gold sarcophagi.
LEVEL 1
Dimensions: 1x1
Construction: Rose Gold Ramp
Tombs(total): 0(0)
Total Rose Gold Used (with furniture): 1(1)
LEVEL 2
Dimensions: 3x3
Construction: one Wall, eight Raps
Tombs(total): 0(0)
Total Rose Gold Used (with furniture): 10(10)
LEVEL 3
Dimensions: 5x5
Construction: 16 Ramps, 8 Walls, 1 floor/wall/down stair
Tombs(total): 0(0)
Total Rose Gold Used (with furniture): 35(35)
LEVEL 4
Dimensions: 7x7
Construction: 24 Ramps, 16 Walls, 1 Down stair/up-down stair, 8 Floors
Tombs(total): 8(
Total Rose Gold Used (with furniture): 84(92)
LEVEL 5
Dimensions 9x9
Construction: 32 Ramps, 24 Walls, 24 floors, 1 stair
Tombs (total): 24 (32)
Total Rose Gold Used (With Furniture): 165(197)
LEVEL 6
Dimensions: 11x11
Construction: 40 Ramps, 32 walls, 48 floors, 1 stair
Tombs (total): 48 (80)
Total Rose Gold Used (With Furniture): 286(366)
LEVEL 7
Dimensions: 13x13
Construction: 48 Ramps, 40 walls, 80 floors, 1 stair
Tombs (total): 80 (160)
Total Rose Gold Used (With Furniture): 455(615)
LEVEL 8
Dimensions: 15x15
Construction: 56 Ramps, 48 walls, 120 floors, 1 stair
Tombs (total): 120 (280)
Total Rose Gold Used (With Furniture): 680(960)
LEVEL 9
Dimensions: 17x17
Construction: 64 ramps, 56-X walls, X Doors, 224 floors, 1 stair,
Tombs (total): 224 (504) -- GOAL MET
Total Rose Gold Used (With Furniture): 904 (1,408)
So, to build a smooth-sided solid rose gold pyramid with room for 400 coffins, it will take 904 rose gold, assuming you pave the bottom level with floors rather than letting it sit on dirt. You will actually have room for 504 coffins, allowing you to place some statues or paths, or otherwise have a little fun.. If you also make the coffins out of rose gold, you will need 1,408 to get your full 540 coffin compliment, a mere 1,304 if you simply make 400 and leave all other spaces blank rather than filled with ☼Rose Gold Statues☼. From base to tip it will be 9z tall.
Good luck.