There is at least one way to tile 3D space using two different nets - The Math overflow answer which provides tilings for all possible nets (https://mathoverfl

There is at least one way to tile 3D space using two different nets - The Math overflow answer which provides tilings for all possible nets (https://mathoverflow.net/questions/199097/which-unfoldings-of-the-hypercube-tile-3-space-how-to-check-for-isometric-space/392828#392828 https://mathoverflow.net/questions/199097/which-unfoldings-o...) gives two which fit exactly into a 4 by 4 by 2 box - https://mo271.github.io/mo/198722/tilings/plots/72.html https://mo271.github.io/mo/198722/tilings/plots/72.html and https://mo271.github.io/mo/198722/tilings/plots/159.html https://mo271.github.io/mo/198722/tilings/plots/159.html. Since a 4 by 3 by 2 box can fill 3D space on it's own, you could alternate boxes using different nets. It's a bit of a cheat though. I would strongly suspect that there are better ways to do it!