The unique feature of the MagSafe is not the magnetic attachment, but rather the microcontroller inside the power brick: It outputs a low-amp 5V until a connect

The unique feature of the MagSafe is not the magnetic attachment, but rather the microcontroller inside the power brick: It outputs a low-amp 5V until a connection has been verified, only then will a full connection be established and the potentially harmful full power delivered. You can duplicate the magnetic attachment for a few dollars, but not the feature that makes it safe to use. (Which is also one of the problems of third-party magsafe power supplies.)