Line an 8-inch square baking pan with plastic wrap that generously hangs over the sides. Arrange cucumber slices in rows, slightly overlapping, to cover the bottom of the pan.
Arrange smoked salmon slices over cucumber.
Spread Wasabi Mayonnaise evenly over the salmon.
Gently spread half the rice on top of the salmon. Sprinkle your hands with water and firmly press down the rice.
Place nori sheet on top of then rice then top with remaining rice pressing firmly into the pan. Fold in sides of the plastic wrap, covering with more plastic wrap if needed. Place a second empty pan on top and fill it with full food cans to compress the rice. Refrigerate for several hours or overnight.
Unwrap and invert onto sushi pizza onto a cutting board. With a sharp knife cut into small squares about the size of the cucumber slices. Place on a serving platter.