In resealable freezer plastic bag, mix chocolate chips and oil; seal bag. Microwave on High 30 to 45 seconds, squeezing chocolate in bag every 15 seconds, until smooth. Cut 1/4-inch tip from corner of bag; drizzle chocolate over bars. Let stand about 1 hour or until chocolate is set. For bars, cut into 8 by 4 rows; cut each bar in half diagonally to make triangles.