Take 1x number from a cell of the first grid with 4x the same 4x4 in 6x6 magic square and add number x 36 from the same cell of the second grid to produce a 12x12 composite magic square.
1x number
1 | 6 | 9 | 34 | 32 | 29 | 1 | 6 | 9 | 34 | 32 | 29 |
35 | 11 | 18 | 23 | 22 | 2 | 35 | 11 | 18 | 23 | 22 | 2 |
33 | 25 | 20 | 13 | 16 | 4 | 33 | 25 | 20 | 13 | 16 | 4 |
27 | 14 | 15 | 26 | 19 | 10 | 27 | 14 | 15 | 26 | 19 | 10 |
7 | 24 | 21 | 12 | 17 | 30 | 7 | 24 | 21 | 12 | 17 | 30 |
8 | 31 | 28 | 3 | 5 | 36 | 8 | 31 | 28 | 3 | 5 | 36 |
1 | 6 | 9 | 34 | 32 | 29 | 1 | 6 | 9 | 34 | 32 | 29 |
35 | 11 | 18 | 23 | 22 | 2 | 35 | 11 | 18 | 23 | 22 | 2 |
33 | 25 | 20 | 13 | 16 | 4 | 33 | 25 | 20 | 13 | 16 | 4 |
27 | 14 | 15 | 26 | 19 | 10 | 27 | 14 | 15 | 26 | 19 | 10 |
7 | 24 | 21 | 12 | 17 | 30 | 7 | 24 | 21 | 12 | 17 | 30 |
8 | 31 | 28 | 3 | 5 | 36 | 8 | 31 | 28 | 3 | 5 | 36 |
+ 36x number
0 | 3 | 0 | 3 | 0 | 3 | 1 | 2 | 1 | 2 | 1 | 2 |
3 | 0 | 3 | 0 | 3 | 0 | 2 | 1 | 2 | 1 | 2 | 1 |
0 | 3 | 0 | 3 | 0 | 3 | 1 | 2 | 1 | 2 | 1 | 2 |
3 | 3 | 0 | 3 | 0 | 0 | 2 | 2 | 1 | 2 | 1 | 1 |
3 | 0 | 3 | 0 | 3 | 0 | 2 | 1 | 2 | 1 | 2 | 1 |
0 | 0 | 3 | 0 | 3 | 3 | 1 | 1 | 2 | 1 | 2 | 2 |
2 | 1 | 2 | 1 | 2 | 1 | 3 | 0 | 3 | 0 | 3 | 0 |
1 | 2 | 1 | 2 | 1 | 2 | 0 | 3 | 0 | 3 | 0 | 3 |
2 | 1 | 2 | 1 | 2 | 1 | 3 | 0 | 3 | 0 | 3 | 0 |
1 | 1 | 2 | 1 | 2 | 2 | 0 | 0 | 3 | 0 | 3 | 3 |
1 | 2 | 1 | 2 | 1 | 2 | 0 | 3 | 0 | 3 | 0 | 3 |
2 | 2 | 1 | 2 | 1 | 1 | 3 | 3 | 0 | 3 | 0 | 0 |
= 12x12 composite magic square
1 | 114 | 9 | 142 | 32 | 137 | 37 | 78 | 45 | 106 | 68 | 101 |
143 | 11 | 126 | 23 | 130 | 2 | 107 | 47 | 90 | 59 | 94 | 38 |
33 | 133 | 20 | 121 | 16 | 112 | 69 | 97 | 56 | 85 | 52 | 76 |
135 | 122 | 15 | 134 | 19 | 10 | 99 | 86 | 51 | 98 | 55 | 46 |
115 | 24 | 129 | 12 | 125 | 30 | 79 | 60 | 93 | 48 | 89 | 66 |
8 | 31 | 136 | 3 | 113 | 144 | 44 | 67 | 100 | 39 | 77 | 108 |
73 | 42 | 81 | 70 | 104 | 65 | 109 | 6 | 117 | 34 | 140 | 29 |
71 | 83 | 54 | 95 | 58 | 74 | 35 | 119 | 18 | 131 | 22 | 110 |
105 | 61 | 92 | 49 | 88 | 40 | 141 | 25 | 128 | 13 | 124 | 4 |
63 | 50 | 87 | 62 | 91 | 82 | 27 | 14 | 123 | 26 | 127 | 118 |
43 | 96 | 57 | 84 | 53 | 102 | 7 | 132 | 21 | 120 | 17 | 138 |
80 | 103 | 64 | 75 | 41 | 72 | 116 | 139 | 28 | 111 | 5 | 36 |
Each 1/2 row/column/diagonal gives 1/2 of the magic sum and the 12x12 magic square is 6x6 compact. In the 12x12 magic square are 4 proportional 4x4 panmagic squares.
I have used method composite, proportional (2) to construct
12x12, 18x18, 24x24, 30x30a and 30x30b