I saw this basic idea on another web site and I added a few twists of my own. The witch is stirring a nasty looking brew pot which as you can see looks like it has a few body parts in it. She cackles hideously and her red glow as she looks back and forth for more victims. A crackling fire glows under the cauldron of steaming potion (the steam is kind of hard to see in this picture).

This is a nice effect and got lots of compliments. Its pretty simple to build, I had a working prototype in half an hour !

The body and head animation use a floor standing oscillating fan. The stand with some packing foam taped to it forms the witches body. I removed the fan cover and blade and mounted the head over the fan motor. The oscillating fan motor gives the witches head a back and forth motion. The head is a latex mask and hood I bought after Halloween a few years back for a few dollars. Its stuffed with bubble pack where needed to fill it out and the glowing eyes are two red LEDs powered by a 9 volt battery.

The arms are jointed so they move as she stirs. I made these out of coat hanger wire bent at the “joints” into interlocking loops (borrowed that technique from the Flying Crank Ghost). The wires are wrapped in bubble wrap to give them a bit of shape. The hands are gloves with stiff wire bent to form fingers, which are formed around the spoon handle she is holding. The robe is from a costume my wife made a few years back.

The brew pot is a large plastic flower pot I found in the garage. I added wooden legs to get it to the right height. I thought of using a tripod and having the pot hang from it on chains but that was getting too complicated.

The stirring mechanism is a small DC gear motor I found at a computer surplus store. On three AA cells it runs about 4 RPM and the power consumption is so low the batteries will last all night.  It is mounted to the bottom of the flower pot roughly in the center with the output shaft pointing up. I mounted an L bracket to the shaft which is about 3 inches on one side - it mustn’t hit the sides of the pot as the shaft rotates (see picture below). To the upright of the L bracket I attached the spoon handle - a piece of dowel. The trick is to use a bearing so the dowel can rotate on its own as the motor rotates - otherwise the dowel will try to twist the hands of the witch as the motor turns. I used a ball bearing assembly salvaged out of a dead disk drive. Bend the wire fingers of the witch around the dowel and use some tape or wire to make them stay where you want. It takes a bit of adjusting of everything to get the witches hands and arms to move freely in a stirring motion.

Finishing Touches

I piled a few logs under the pot and put a red light in the middle to simulate a fire. Very simple but it looks really good in the dark, especially with fog pouring over the sides of the pot. I put a speaker under the robe and used my PC to play witch cackles and boiling cauldron sounds in an endless loop.

The Steam - I piped the output of my fog machine through a fog cooler into the bottom of the pot. You can see the pipe in the picture above. This really looked great - the cooled fog rolls over the edge of the pot and drifts onto the ground, glowing in the “firelight”. The fog machine is a very neat design I saw on somebody’s site. Its documented on my “halloween” page too.