In this realization four symmetric redundant parity checks are added to the parity check matrix from realization 1:
|   1 1 1 0 1 0 0 0   | |
|   1 1 0 1 0 1 0 0   | |
|   1 0 1 1 0 0 1 0   | |
|   0 1 1 1 0 0 0 1   | |
H' |
|   0 0 1 1 1 1 0 0   | |
|   0 1 1 0 0 1 1 0   | |
|   1 1 0 0 0 0 1 1   | |
|   1 0 0 1 1 0 0 1   | |
We get the following realization: