... In a gig you probably want the numbers constrained in spacetime in a reasonable way so that the audience don't have to wait millions of years for it to come back to a useful range.
Probably...the thing about Perlin noise (as I understand it now) is that it is predetermined, backwards from the idea of a random walk: you input two or three numbers and get as output a random number that is always the same for the same input, always similar for a nearby input, and uncorrelated for distant inputs. So it's like a surface that you can do a random, or any other kind of walk on. It's usually used in computer graphics to make terrain and texture. In 3D it can make 3D textures like marble or bread.
I suppose a pd 3D perlin object would have three inlets (plus messages to set parameters) and one outlet, and the random values would need to be calculated once and for all at init, or whenever the parameters change, so it would be a memory hog.
Martin