-a clean plastic bottle
-anything small enough to fit inside- paper clip, lego, crayon, button, hair pin, ect.
-pen and paper
Collect your treasures and drop them in, writing each one down as you go. Then funnel in the rice/sand until it is about an inch from the top, leaving a little room from the rice or sand to move around.
Super glue the cap so you don't have any messes.
Screw on the cap and start hunting!