class Board:
    def __init__(self, board = None):
        if not board:
            self.board = [[0 for i in range(8)] for j in range(8)]
        else:
            self.board = copy.copy(board)

class PossibleBoard(Board):
    def __init__(self, level, free_cells, parent, brd=None):
        Board.__init__(self, board = brd)
        self.level = level
        self.free_cells = free_cells
        self.parent = parent
        
class Work:
    def __init__(self, figures):
        self.figures = figures
        self.board = PossibleBoard(0, 64, None)
        self.result = [list() for i in range(len(self.figures)+1)]
        self.result[0].append(self.board)
    
    ...

    def set_queen(self, brd):
        for x in range(8):
            for y in range(8):
                if not (brd.board)[x][y]:                    
                    tmp_board = PossibleBoard(self.level,
                                                brd.free_cells-1,
                                                copy.copy(brd),
                                                copy.copy(brd.board))
                    (tmp_board.board)[x][y] = 'Q'
                    for i in range(8):
                        for j in range(8):
                            if (i==x or j==y or (abs(x-i)==abs(y-j)) ) and tmp_board.board[i][j]==0:
                                tmp_board.board[i][j] = 1
                                tmp_board.free_cells-=1
                    
                    self.result[self.level].append(tmp_board)

>>> import copy
>>> a = [[],[],[]]
>>> b = copy.copy(a)
>>> c = copy.deepcopy(a)
>>> print id(a), [id(a[i]) for i in xrange(3)]
3073918252 [3073918124L, 3073918092L, 3073918284L]
>>> print id(b), [id(b[i]) for i in xrange(3)]
3073931276 [3073918124L, 3073918092L, 3073918284L]
>>> print id(c), [id(c[i]) for i in xrange(3)]
3073931180 [3073919372L, 3073931244L, 3073931340L]

import copy
rows=2  # число строк в исходной матрице (будет потом расчетное)
columns=3 # число столбцов в исходной матрице  (будет потом расчетное)
z=None

matr_rev = [[z]*rows]*columns # готовим  матрицу из элементов None
print(matr_rev)

matr_rev2= copy.deepcopy(matr_rev) #глубокая копия
matr_rev2[0][1]=2   #вставка 1 элемента
print(matr_rev2)

>>> rows, cols = 2, 3
>>> matr = [[None for j in range(cols)] for i in range(rows)]
>>> matr[0]
[None, None, None]
>>> matr
[[None, None, None], [None, None, None]]
>>>

>>> x, y, z = 2, 3, 4
>>> matr = [[[None for k in range(z)] for j in range(y)] for i in range(x)]
>>> matr[0][0][0] = 1
>>> matr
[[[1, None, None, None], [None, None, None, None], [None, None, None, None]], [[None, None, None, None], [None, None, None, None], [None, None, None, None]]]
>>>