This personalized candle holder displays a silhouette of my family on the wall and some text on a table using only the light from a little tiny votive candle. If done correctly, the shadow will be indifferent to the specific height of the wick and flame (within the typical sizes for votive candles that is).
Instead of hanging a photo with nails, or a mural with wallpaper/paint, the candle holder...and thus the shadow, can be swapped out easily for different occasions, even during the daytime hours!
Also note that I rely heavily on annotating my images in this instructable since the easiest way to see what I’m doing is with a screen capture (Shift-Command-3), upload, and click for an instant note. Except for a few rarities, every image is tagged somewhere, so if you see a blank one, look for a itsy square crammed at the top of the image. Sometimes, I see this happening on both mine and other’s ‘ibles and I don’t know why. Clicking on the next image and then going back sometimes repairs the problem.
Parallels 7 running Windows 8 (AutoDesk is working on a Mac Version of 123D, but not yet out)
Step 1: Decide on an environment for your shadow
The lighting and environment all need to be thought through and will determine the form of shadows that you can create.
You are not limited to a single surface. Actually, you can project a shadow through multiple rooms in your house that only makes sense from one perspective if you like (example: http://www.archivenue.com/wp-content/uploads/Geometric-Illusionary-Perspective-Paintings-1.jpg). Cast it on the ceiling, or both the table and wall simultaneously as I did.
Consider permanent obstacles, such as the chair in my photo...or dynamic ones, such as a person if they happen to sit in said chair.