Turn an empty shoebox onto one of its sides. Determine which side will be the ground of the diorama.
Press air-drying clay onto the ground of the box, forming it into hills and valleys to represent the Oregon Trail. Allow to dry completely.
Paint the clay with green and brown acrylic paint. Allow to dry.
Paint the inside of the box with blue acrylic paint to represent the sky. Paint a large snow-covered mountain on one side of the box to represent the mountains seen in Oregon. If you want one side of the box to be a hillside, paint trees on it with green and brown paint. Allow the paint to dry.
Cut out pictures from construction paper to represent images seen in Oregon and on the Oregon Trail, such as a covered wagon, horses, bears and pioneers. Tape the pictures into the diorama.
Cut out a rectangle from poster board measuring 1 by 4 inches.
Write a title on the rectangle with markers, such as "Oregon" or "The Oregon Trail." Tape the title to the top of the box, which is now ready for display.