You could use water material, render will be done by the game. However, that would mean you should add "Level" blockstate (like fluids) to avoid crashing the game.
This method work and is easy to implements however there are some render glitch near non-opaque blocks (expect water), glass for instance.
Or as diesieben07 said, you could create a block model, but it's more difficult I think. (For side rendering)