First, I will wait until the day before St. Patrick’s Day.  Second, I will take an empty milk carton, fill it with fake grass, and then put a chocolate coin in it.  Third, I will take a string, tape it to the ceiling, and attach a DIY lid for the empty milk carton (that automatically seals tightly onto the empty milk carton so the leprechaun can’t get out) onto the string.  Fourth, I will attach another string to the coin and attach the other end to a robot.  Fifth, I will program the robot to drive over to the string attached to the lid with scissors and cut it when it senses that a leprechaun is in the trap.  The lid will fall onto the empty milk carton, thus trapping the leprechaun.  On the morning of St. Patrick’s Day, I should see a leprechaun in my trap.