It is totally your choice. But it has been observed that creating a physical mood board offers relatively greater scope to experiment with than the digital ones. With digital mood boards, you will be using pretty much the same tools that you use on a daily basis for your design project. But, with a physical mood board, you have the entire physical world to take inspiration from and add those elements to your own mood board. If you are talking about a beach, you can add sand or shells to create a real-like feeling. While physical mood boards do require a lot of hard work, the results can be exceptional, making it truly worth your while.