The problem with doing this is you won't get the MAC of the target machine. You'll end up getting the MAC address of the near-side interface of the router closest to your machine in the network path to the target.
You might want to
read up on what a MAC address is[
^] and what it's used for in the network world before trying to use it for something it was never designed for. Really, there is no use for a MAC address outside of networking.