You have probably seen them in museums, haunted houses, and other places -- fake flames. Here's one that I built, after finding that cellophane actually does a much better job at imitating flames than flame-coloured tissue paper.
You will need the following materials:
A 12-volt DC power supply, about 300mA rating or higher will do
A standard cheap string of Christmas lights (they usually come in 48 or 50 lights per string) ($3.49 at iParty)
A cauldron ($1.99 at iParty)
Sheets of thin cellophane (~$3/roll) at iParty
A 12V CPU fan
A durable plastic plate that will just fit onto the top of the cauldron (Whole Foods has excellent reusable highly durable plastic plates that nicely lock into the lip of the iParty cauldron.
and of course some basic electronics tools and skills.
First, cut a hole in the bottom of the cauldron. This may be harder that it sounds to do safely, be careful about slippage when cutting plastic with a knife. This hole is for air to get into the cauldron from the bottom.
Then, cut a hole into the plastic plate and glue the CPU fan onto the back, making sure you have the airflow in the correct direction as well as making sure you don't get glue onto the fan blades, for obvious reasons.
Now, get a string of cheap Christmas lights and cut a series string of 5 lights out of them. Since each light is rated for 2.5 volts (hence 2.5 volts/light * 48 lights is about 120V), 5 lights can be powered by about 12 volts. Make sure nobody else in your household will accidentally plug in the rest of the string into the wall socket after you cut out a few lights!
Now, get some thin, floppy cellophane (I tried different colours and ended up using the red cellophane, although I really imagine clear cellophane would be the best because we intend to create the flame effect not by lighting up the cellophane's surface but by reflecting the incandescent lights).
Cut out just one or two small, ~5-8cm flame-like shapes of it, and tape them onto the rigid parts of the fan or the plate in a way that causes them to flutter wildly when the fan is run. Connect the fan and string of lights in parallel to the 12V supply and check it out:
Now, suspend it in the air so it can actually blow air up! You may have to do a lot of tuning up of exactly how you tape down the cellophane, at what angle, etc. so that it reflects the incandescent lights at the viewer. When you have it right, you'll be rewarded with a very realistic-looking flame in the dark.
