In order to get the mould you need to go to the building east of the magic stall on Ape Atoll. If you don't already have a greegree, you must stay in the dark area. Search the southeastern most crate to uncover a hidden entrance into the Temple of Marimbo Dungeon. Dropping down this entrance may yield some significant damage. Watch out for spiders, as they can poison. In the northwest corner there's a cluster of crates around a stalagmite; the moulds are in the crate directly south of the stalagmite.