Cover the foam ball and the top of the bottle with cling film, pressing it smooth so it does not create lumps under the fabric. Balance the foam ball on top of the bottle neck; this is your ghost form. Pour the fabric stiffener into the shallow bowl. Submerge the muslin in the stiffener, working it in with your hands until fully saturated. Lift it out and squeeze gently (do not wring) to remove excess, so it is wet and limp but not dripping.

Drape the saturated muslin over the foam ball and bottle form, centring it so the ball is under the highest point of the fabric. Arrange the lower edges into soft, uneven folds, pulling downward to taper the hem. Lift one corner slightly on each side if you want the suggestion of raised arms. Work quickly: you have about ten minutes before the stiffener begins to set. Once you are satisfied with the shape, do not touch it again.

Leave the ghost to dry completely in a warm place, at least six to eight hours or overnight. When fully dry, the muslin will be rigid and hold its shape without support. Slide the bottle out from below and peel the cling film away carefully; the foam ball will stay inside the head and that is fine. The ghost should stand on its own.