I have been fascinated by the hologram scenes in Star Wars since I was a little boy. This Halloween, I decided to create the similar effect using a home made fog screen.
Fog screen is an "immaterial" projection screen that consists of air and a little humidity, and enables high-quality projected images in thin air. The image floating in thin air encourages kids to play with it.
However, most fog screen designs are either expensive or complicate to operate. We often need to control the temperature and the air flow at the same time. Some widely used ingredients such as dry ice and hot oil are also dangerous to kids. So I build a simple desktop fog screen for my daughter using a low cost ultrasonic humidifier. My humidifier costs $39.99. And it is the most expensive part. This process is also very straight forward. It took me about 2 hours. The operation of humidifier naturally creates the fog screen as a by-product. We do not need to think about adding dry ice or any fog solution. And my daughter loved it.
Another happy Halloween just past. Here is how I made it.
Step 1: What you'll need
iPod or computer
Washing machine drain hose ( Inlet 1-1/8'' to 1-1/4''' or 28 mm-32mm)
About 50 bendable straws
Wood photo frame (without glass) or iPad stand
Teflon tape (thread seal tape)
Step 2: Test and clean humidifier
If necessary, you can clean your old humidifier with white vinegar.
Step 3: Make a two-hinge bendable straw
A normal bendable straw has only one concertina-type hinge near the top, and it is still not flexible enough to guide and change the air flow. What we need is a straw with at least two hinges.
We can make a two hinge straw by connecting two normal straws with a layer of Teflon tape and a layer of regular packing tape. The purpose of using Teflon tape is to create a water proof layer between two straws and the packing tape.