Some solutions with all values from 0 to 6 for 7 X 7 X 7:
........0..............0..............0..............0..............0
.......1.1............2.2............1.1............1.1............2.2
......1.6.1..........2.5.2..........1.6.1..........1.6.1..........2.5.2
.....0.1.1.0........0.2.4.2........0.1.1.0........0.1.1.0........2.4.2.0
....0.2.2.2.2......1.1.2.0.2......0.2.2.2.2......2.2.2.2.0......2.5.2.1.1
...3.2.0.4.5.2....1.6.1.2.2.0....3.2.5.4.0.2....2.5.4.5.2.3....0.2.2.1.6.1
..0.0.2.2.2.2.0..0.1.1.0.0.3.0..0.0.2.2.2.2.0..0.2.2.2.2.0.0..0.3.0.0.1.1.0