you need 7 orichalcum+, because there are only 7 in the game. I can only remember a couple of the places where you get them though
Finish Atlantica
Finish Goddess of fate cup, which opens after beating Xigbar
Finish 100 acre woods
Theres small chest in Twilight town near sunset hill on a platform
chest in Space paranoids right before the MCP
Theres a chest in The world that never was near the first savepoint.
Obtain all of the materials in the game by whaling on every heartless of every world with the sweet memories keyblade. the moogle gives you one automatically.
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wait thats all of them, whaever.
also, you need some dense crystals and twiligt crystals.
sorcerers( the nobodies with the boxes) give of T. crystals.
Berserkers ( nobodies with the big hammers) give you D. Crystals.
Icant remember the rest of the ingredients, sorry.