There are a number of ways to make ice cream without a machine. Perhaps the easiest is as described above, using a regular freezer, and stiring at intervals. The fastest is to mix the base with a couple volumes of liquid nitrogen, which gives you ready to eat ice cream in ten seconds. It's helpful to understand what the ice cream mixing machine does, in order to consider what you need to do to get a suitable product. Consider the clasic hand-cranked sort. The basic idea is that the dashers agitate the ice-cream-to-be, while the can rotates in the ice/salt mixture. The dashers agitate the ice-cream-to-be helps prevent the ice cream from freezing into big crystals of frozen water, and also entrain some air into the frozen mixture, which reduces the density, makes it a bit softer, and probably changes the mouth-texture. Rotating the can keeps the freezing ice/salt mixture in motion, which ensures that the can is always in contact with the coldest part of the mixture; that reduces the amount of time it takes to freeze the mixture. That's good, both because it's faster (less cranking! yeah! eat it sooner!) and because it reduces the production of ice crystals.
Using liquid nitrogen certainly accomplishes the freeze fast bit, and gets some overrun (air entrained in the frozen mixture) from the stiring and from the nitrogen itself. Unless you've got a friendly cryogentics facillity or chemist, it's rather hard to get small volumes of liquid nitrogen.
Putting the bowl in the freezer and stirring every hour or so is easy. It doesn't produce terribly good results, though. It'll tend to have big ice crystals in it, won't freeze as hard as you'd like, and takes a long time.
Another method -- and the one I use -- is to put a small volume of base in a large ziplock bag, and then put the sealed bag into a salt/ice mixture. I use about a pint or pint and half of base into a two gallon ziplock, which goes nearly flat (so as to maximize the surface area exposed to the ice/salt. Squeeze all the air out, too.) onto a bed of ice, and then is covered in more ice/salt. Let sit for 20 minutes or so, take out of the ice, knead the starting to freeze mixture, put back in the ice for another 20 minutes. If you stop before it's solidly frozen, you can put the ice cream in a more elegent container. If you don't, you may have to slice the bag open to get it out.
Any others?
Using liquid nitrogen certainly accomplishes the freeze fast bit, and gets some overrun (air entrained in the frozen mixture) from the stiring and from the nitrogen itself. Unless you've got a friendly cryogentics facillity or chemist, it's rather hard to get small volumes of liquid nitrogen.
Putting the bowl in the freezer and stirring every hour or so is easy. It doesn't produce terribly good results, though. It'll tend to have big ice crystals in it, won't freeze as hard as you'd like, and takes a long time.
Another method -- and the one I use -- is to put a small volume of base in a large ziplock bag, and then put the sealed bag into a salt/ice mixture. I use about a pint or pint and half of base into a two gallon ziplock, which goes nearly flat (so as to maximize the surface area exposed to the ice/salt. Squeeze all the air out, too.) onto a bed of ice, and then is covered in more ice/salt. Let sit for 20 minutes or so, take out of the ice, knead the starting to freeze mixture, put back in the ice for another 20 minutes. If you stop before it's solidly frozen, you can put the ice cream in a more elegent container. If you don't, you may have to slice the bag open to get it out.
Any others?
