This section is from the book "The Boy Mechanic Vol. 2 1000 Things for Boys to Do", by Popular Mechanics Co.. Also available from Amazon: The Boy Mechanic, Vol2: 1000 Things for Boys to Do.
Obtain a stick for the hem on the lower end of the shade that is 2 in. longer than the shade is wide. Place two small wood screws in the window casing below the shade roller in such a position that they will catch the ends of the stick when the shade is raised to the top. - Contributed by Harry E Kay, Ossining, N. Y.