Try it if you can! It is fantastic fun, and incredibly easy! You'd be amazed. Each of these pics only took 30 seconds of exposure time, and maybe 3 or 4 minutes to set the camera up on a tripod. If you've only got 20 minutes, you can still get a bunch of really neat pictures.

You can actually write or paint on the film in the same way...using any light source. We set up in our living room and my wife draws pictures of flowers using a laser pointer. We call it digital charades or digital pictionary. lol. I'm making some LED tools that people can use to make these, and giving classes at my local library next month teaching people how to do this.