You Asked:
Can you make your own dry ice? — Ian, Markham, Canada

Marshall Brain Answered:

Let’s start by looking at how they make dry ice at a dry ice factory:

As the video states: “When liquid CO2 is released into a non-pressurized environment, most of it turns into dry ice show.” You compress the snow in a mold to make a block of dry ice. This little device is called the Frigimat dry ice maker. you attach a pipe from a tank of liquid CO2 to the device to capture the snow:

You can buy liquid CO2 in tanks. A CO2 fire extinguisher is just a tank of liquid CO2 with a valve and a nozzle.

Dry ice is one of those things, however, where it is probably much cheaper to buy it already made. Many grocery stores now sell it, or look for a manufacturer in your local area.

See also: What if I touched dry ice?