@foone Is it even possible to fill a klein bottle? I mean, it's a bit like a möbius strip, there is no inside and outside surface, but only one surface, so there should be no inside, no volume to be filled, either, right? So it's basically "open" everywhere, within 4D space?
@DPA they just have to define a klein bottle in a space where both sides are full of milk. fortunately that's easy to ensure since they have infinite cows