Because people overlook that you can rotate a symmetry modifier and I thought it was worth mentioning. Also if your working smaller than 1/4th you'll need to rotate it, not really sure how small or big he wants to make his modules, I picked 1/4ths because it was easier for me to write up, ha.
Oh wow, this looks pretty pimp! I really dig the composition in the 1st, 2nd, and 4th shot, with the 4th being my favorite. Your transition from the ground to the water looks a little rough...maybe darken the ground near the edge where it gets wet or place some pebbles near the edge or something. Good work man