The stream part has been adjusted to fit well within the skull cavity. The skull itself is a copy of the "Skull Bowl Remix..", the only change being in scaled size. The skull must be printed with supports (which worked pretty well, though it's a complicated model and takes a while to print). The stream and splash parts are scaled to 80% of the size of the "Floating Cup" from which they were derived. Scale all parts equally as you need (but they would have to be scaled much more for the skull to ever approach a human skull size!).