Q;S⁹o_                  Helper link.
                        Arguments: [k, 0, k] and [0, m, 0] (any order)

Q                       Unique; deduplicate the left argument.
 ;                      Concatenate the result with the right argument.
  S                     Take the sum of the resulting array.
   ⁹o                   Logical OR with the right argument; replaces zeroes in the
                        right argument with the sum.
     _                  Subtract; take the difference with the right argument to
                        remove its values.
                        This maps [k, 0, k], [0, m, 0] to [0, k + m, 0] and
                        [0, m, 0], [k, 0, k] to [m + 2k, 0, m + 2k].


3ḶḂç@⁸СIµa"Ṿ€o⁶z⁶Zµ€Z  Monadic link. Argument: A (array of column indices)

3Ḷ                      Yield [0, 1, 2].
  Ḃ                     Bit; yield [0, 1, 0].
        I               Increments of n; yield [].
      С                Apply...
   ç@                       the helper link with swapped arguments...
     ⁸                      n times, updating the left argument with the return
                            value, and the right argument with the previous value
                            of the left one. Collect all intermediate values of
                            the left argument in an array.
         µ         µ€   Map the chain in between over the intermediate values.
            Ṿ€          Uneval each; turn all integers into strings.
          a"            Vectorized logical AND; replace non-zero integers with
                        their string representation.
              o⁶        Logical OR with space; replace zeroes with spaces.
                Z       Zip; transpose the resulting 2D array.
                   Z    Zip; transpose the resulting 3D array.

Q;S⁹o_                  Helper link.
                        Arguments: [k, 0, k] and [0, m, 0] (any order)

Q                       Unique; deduplicate the left argument.
 ;                      Concatenate the result with the right argument.
  S                     Take the sum of the resulting array.
   ⁹o                   Logical OR with the right argument; replaces zeroes in the
                        right argument with the sum.
     _                  Subtract; take the difference with the right argument to
                        remove its values.
                        This maps [k, 0, k], [0, m, 0] to [0, k + m, 0] and
                        [0, m, 0], [k, 0, k] to [m + 2k, 0, m + 2k].


3ḶḂç@⁸СIµa"Ṿ€o⁶z⁶Zµ€Z  Monadic link. Argument: A (array of column indices)

3Ḷ                      Yield [0, 1, 2].
  Ḃ                     Bit; yield [0, 1, 0].
        I               Increments of n; yield [].
      С                Apply...
   ç@                       the helper link with swapped arguments...
     ⁸                      n times, updating the left argument with the return
                            value, and the right argument with the previous value
                            of the left one. Collect all intermediate values of
                            the left argument in an array.
         µ         µ€   Map the chain in between over the intermediate values.
            Ṿ€          Uneval each; turn all integers into strings.
          a"            Vectorized logical AND; replace non-zero integers with
                        their string representation.
              o⁶        Logical OR with space; replace zeroes with spaces.
                z⁶      Zip with fill value space; transpose the resulting 2D
                        array after inserting spaces to make it rectangular.
                  Z     Zip; transpose the result to restore the original shape.
                     Z  Zip; transpose the resulting 3D array.

How it works

Q;S⁹o_                  Helper link.
                        Arguments: [k, 0, k] and [0, m, 0] (any order)

Q                       Unique; deduplicate the left argument.
 ;                      Concatenate the result with the right argument.
  S                     Take the sum of the resulting array.
   ⁹o                   Logical OR with the right argument; replaces zeroes in the
                        right argument with the sum.
     _                  Subtract; take the difference with the right argument to
                        remove its values.
                        This maps [k, 0, k], [0, m, 0] to [0, k + m, 0] and
                        [0, m, 0], [k, 0, k] to [m + 2k, 0, m + 2k].


3ḶḂç@⁸СIµa"Ṿ€o⁶z⁶Zµ€Z  Monadic link. Argument: A (array of column indices)

3Ḷ                      Yield [0, 1, 2].
  Ḃ                     Bit; yield [0, 1, 0].
        I               Increments of n; yield [].
      С                Apply...
   ç@                       the helper link with swapped arguments...
     ⁸                      n times, updating the left argument with the return
                            value, and the right argument with the previous value
                            of the left one. Collect all intermediate values of
                            the left argument in an array.
         µ         µ€   Map the chain in between over the intermediate values.
            Ṿ€          Uneval each; turn all integers into strings.
          a"            Vectorized logical AND; replace non-zero integers with
                        their string representation.
              o⁶        Logical OR with space; replace zeroes with spaces.
                Z       Zip; transpose the resulting 2D array.
                   Z    Zip; transpose the resulting 3D array.

Jelly, 31 30 bytes

ø3ḶḂðQ;S⁹o_µ@С“”µa"Ṿ€o⁶z⁶Zµ€Z

This is a niladic link that reads a 0-based column index from STDIN and returns a list of strings.

Try it online!

Jelly, 31 30 29 bytes

Q;S⁹o_
3ḶḂç@⁸СIµa"Ṿ€o⁶z⁶Zµ€Z

This is a monadic link; it accepts a 0-based column index as argument and returns a list of strings.

Try it online!