Some solutions with all values from 0 to 6 for 7X7X7
........0..............2..............1..............0..............0
.......2.0............2.2............0.1............0.0............0.0
......2.2.0..........0.3.0..........2.1.4..........0.6.0..........0.6.0
.....0.0.5.0........0.0.5.0........2.2.1.1........0.0.0.0........0.0.0.0
....1.3.0.0.0......1.3.0.0.0......0.0.0.3.0......3.0.2.2.1......1.3.0.5.0
...1.4.3.0.6.0....1.4.3.0.6.0....0.6.0.5.0.3....0.5.0.2.4.1....1.4.3.0.2.0
..0.1.1.0.0.0.0..0.1.1.0.0.0.0..0.0.0.0.0.3.0..0.0.0.0.1.1.0..0.1.1.0.2.2.1