my @all;
foreach my $x (0 .. $#tmp){
  foreach my $y (0 .. $#tmp){
    $all[$x]->[$y] = $tmp[$y]->[$x];
  }
}

# or
my @all = map { my $x = $_ ; [ map { $tmp[$_]->[$x] } 0 .. $#tmp ] } 0 .. $#tmp;

# or do:
my @all = ( \@arr1, \@arr2, \@arr3 );
and then in-place swap (i,j) with (j,i) ..  but this will modify the original @arrX arrays.