Caveman costumes have been used for many years, but since "The Flintstones" premiered in 1960, cavemen costumes have been popular every Halloween. No Flintstone costume is complete without the self-propelled Flintstone car. The car can be made easily in your own home out of materials from your local craft or office store. The ideal box for an adult is 3 feet long, 2 feet wide and 1 foot high. You can easily adjust these proportions to fit a child.
Cut out the top and bottom of the cardboard box. Draw the "log" sides of the Flintstone car on both of the long sides of the cardboard box so that the ends of the logs are drawn to the ends of the box. Draw the wheels of the car by making four identically sized circles at the ends of the two logs.
Turn the box so that the short side is facing you and draw the front wheel by drawing a horizontal straight line that is lined up with the top of the left wheel and the top of the right wheel. Draw another parallel line from the bottom of the left wheel to the bottom of the right wheel. Repeat with the back of the box.
Cut out the lines of the log and wheels while still keeping all of the sides attached. Paint and set is aside to dry.
Mark the middle of the long side of the car lightly with a pencil. Make one dark mark 6 inches to the left of it and another 6 inches to the right. Poke a small hole 1 inch below each of the dark marks with the tip of a knife.
Create a shoulder loop with the twine by tying a double knot underneath the head of one of the double-prong clasps, slipping it through the inside of one of the holes and opening the prongs. Step inside the car and lift the box to wherever feels it comfortable. Wrap the connected twine over your shoulder to determine the length of the shoulder loop. Cut the end of the twine and knot it around another double-prong clasp before slipping it through the other hole and opening the prongs. Repeat the process on the other side of the car.