Subtraction Polygons

Consider the subtraction game that goes like this: Write down one whole number at each corner of the square below, then fill in each side with the positive difference the two neighbouring corners and connect the four new numbers in a smaller square.  Repeat the subtraction to continue forming new squares in the middle.

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3D Sudoku

Imagine instead of a two dimensional grid, we are now filling a 3D grid made up of nxnxn unit cubes with numbers 1 to n such that every row, column, and depth has exactly one of each number.

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