Cook rice. Let steam after cooking for 20 minutes, then put into large mixing bowl and add 1 cup of cooled vinegar sauce. Toss rice lightly but thoroughly with vinegar sauce.
When rice is cooled, spread it about 1 inch thick on a sheet of nori, leaving about 1 1/2 inches uncovered at one edge of nori to use as a sealing flap. Wet fingertips in leftover vinegar sauce to make rice easier to handle.
Place crabmeat and cucumber in a thin line across the rice. Roll the rice into a cylinder, nori side out and crabmeat in the middle. Use a bamboo sushi roller or an acrylic sushi press.Slice across the sushi roll into 8 pieces and serve. Makes about 6 rolls.