Cosmic ray diagram from PhysicsOpenLab.org

The tank ran on dry ice below a metal sheet which cooled isopropyl alcohol into supersaturated vapor that condensed upon interaction with alpha particles, electrons/positrons, and cosmic ray muons.

I ended up cutting a piece of foam so that the dry ice had a nice place to sit.

In an early run of the tank, I got to see a lot of particles for the first time.

The final tank had side lighting to accentuate the vapor trails.

Some examples of different particles:

Alpha particles have wide trails

Electrons are thin and change direction often

Muons are thin but travel in a very fast straight line

Because the concept is so simple I've actually been able to rustle up smaller versions of the cloud chamber whenever dry ice is available. Sometimes a vendor of adhesives will send dry ice in their packaging and isopropanol, a metal sheet, and a clear container are relatively easy to find and put together.