You can make ice cream with a coffee can quite easily, although you will need some supplies in addition to the coffee can. One of the advantages to making ice cream this way is that it is cheap and easy, and many people find it very enjoyable as well. If you don't make ice cream very often, using the coffee can technique is generally preferable to purchasing an ice cream maker, as ice cream makers can be expensive and they tend to eat up space in the kitchen. You can also make ice cream with a coffee can as a class project in school or as a introduction to cooking with young children.
To make ice cream with a coffee can, you are going to need: a large coffee can, a smaller airtight can which will fit comfortably inside, some ice, rock salt, and, of course, ice cream base. You can find recipes for ice cream base in many cookbooks, and it is also possible to purchase ice cream base or ice cream mixes in the store. For rich, creamy ice cream, use a French style custard base, while for ice cream which requires a little less work, you can try New York style ice cream, which is made with just cream, milk, sugar, and flavorings, usually with four parts of an equal cream and milk mix to one part sugar.
Start by washing out your airtight smaller can very carefully, checking to ensure that it is watertight in the process: if water stays in the can when it is sealed, this means that icy, salty water will not seep in from the outside when you make ice cream. You can often use a small coffee can for this purpose, although travel mugs can also work very well, as long as they have tops which can be locked down. While you can use a plastic container, metal is better, as it will conduct the cold more effectively. Some people even use plastic bags which can be tightly sealed instead of solid containers. Fill the container with your ice cream base, but be aware that the ice cream expands as it freezes, so leave lots of breathing room: no more than 1/3 of the container should be filled with ice cream base.
Next, make a layer of ice and salt on the bottom of the larger can. The salt lowers the freezing temperature of the ice, making the container colder than it would be with ice alone. Insert your sealed smaller container, and pack ice around the side and top, so that it is totally surrounded with ice. Finally, secure the lid onto the larger can.
Find a hard floor and a wide flat space, along with a partner. Roll the coffee can back and forth between you for eight to 10 minutes, and then carefully open the can, remove the inner container, and check the consistency. If the ice cream has not set, put the re-sealed inner can back into the larger can, add more ice and salt to the packing, seal the can, and roll for eight more minutes, at which point it should have hardened.
When you make ice cream in a coffee can, condensation tends to appear around the outside of the can. For this reason, it can be a good idea to work outside, or to work on a floor which can be easily cleaned. The coffee can may also scuff tile or wood floors, which is something to consider when selecting a location.