In physics, we regularly deal with observables, which are functions $f(x,y,z)$ of the position vector $\vec r = (x,y,z)$. How, do you plot such a function?
For functions $y=f(x)$ of 1 parameter, we use regular $x$-$y$ line or scatter plots. (These are sometimes called 2D plots.)
For functions $z=f(x,y)$ of 2 parameters, we can use contour/density or surface plots (and modern plotting tools render them nicely.) The latter are often called 3D plots.
For functions $f(x,y,z)$, I'm at a loss. How do I plot/visualize a three-dimensional density? The best approach I have seen so far is a set of two 2D-density plots $f(x,0,z)$ and $f(0,y,z)$ for the intersections with the $x$-$z$ and $y$-$z$ plane.
The final plot shall be printable, i.e. convey the message without relying on animation or user interaction.