i want to make a small amount of dry ice (like the volume of an ice cube).
i only need it every so often, and it's expensive to buy an entire 10 pound block from the grocery every time i need it.

I have a few paintball CO2 tanks, 20 ounces, which are filled with a quantity of liquid CO2. they're all empty, because i haven't used them in a long time, but would it be possible to invert the tanks and spray liquid CO2 out, which then solidifies into solid dry ice?

if so, what precautions would i need to take to do this safely?