Ref: https://en.wikipedia.org/wiki/Squaring_the_square
A perfect cubing of a cube is a partition of the cube into some finite number of smaller cubes that are pair-wise non-congruent. The above page gives a nice proof that perfect cubing is impossible.
- How to cut a cube into the least number of cubes so that only 2 of the smaller cubes are mutually congruent?
Note: Whether this construction is possible or not, we can replace 2 with 3, 4... to generate other questions (obviously, if 8 of the smaller cubes can be congruent, the problem becomes trivial). Alternatively, one can consider 2 pairs of mutually congruent cubes etc.
These questions could have analogs in higher dimensions.