Instructables

Step 6: Smoke Generator (Important tips included)

This step is essential to the tunnel since you need some kind of indicator to be able to see the approximate wind flow. As to what the smoke is out of, we first tried using incense for the smoke.  This was a horrible idea since we were stuck testing with this in a dark, closed garage with airflow from a fan for 3 hours.  Incense also clogs up the tubing over time and we constantly had to clear the tubing and reignite the incense if it ran out.  The single most important tip I would give is to use dry ice and warm water if you have access to it.  The purpose of the water is to speed up the process of creating smoke since the cooler the temperature of the system, the less likely the ice wants to sublimate into CO2 gas.  It is also cleaner and doesn't clog up the tubing as much.  Only downside is that you need a water catcher under the tubing when the cold air condenses inside the tubing creating water. 
The first image is what you want to make.  Refer to the bottom right corner of the design diagram on step 1 for details. 

Basically, you will need the following to make this
~Materials
-Jar w/ lid
-Hand pump of some kind
-1+ ft of Airline tubing (fish tank) 
-Hot Glue/ Water tight sealant
-Incense / Dry Ice + warm water

~Tools
-Drill w/ right bit for the tubing and pump head to fit into


WARNING: NO MATTER WHICH WAY YOU DECIDE TO GO, PROCEED WITH CAUTION AND AT YOUR OWN RISK.  IF USING INCENSE BE SURE TO AERATE THE ROOM AND BREATHE IN AS LITTLE OF THE SMOKE AS POSSIBLE.  IF USING DRY ICE, BE SURE TO WEAR GLOVES AND HANDLE WITH CARE SINCE IT CAN STICK TO SKIN WITH DIRECT CONTACT AND CAUSE SEVERE INJURY.  DO NOT BREATHE THE GAS FROM THE ICE SINCE IT IS CARBON DIOXIDE AND YOU NEED OXYGEN TO LIVE. 


An idea is a small fog machine. Most have a speed control for the amount of fog as well.
nalipaz1 year ago
Might want to caution against the amount of pressure from dry ice and water inside of a glass container as well. Possible you could crack the glass without adequate ventilation.