Word ladders are a relatively easy stereo effect to draw by hand. Print a phrase on a sheet of graph paper, centering one word per line. Place the sheet on a light box. Center your phrase on the left side of a card, and trace the first word. Then, trace the second word, but move it over a bit to the left. Trace the third word, moving it a bit more to the left; and so on. Repeat the process for the right half of the card; but move each word more to the right.
Place the finished card in a stereoscope, and the words will seem to get farther away; cross your eyes (without a stereoscope), and they will seem to get closer.
(Posted by Doug Skinner)