There are two types of ice cream machine on the market today (unless you can find an old crank handled model that you fill with ice and churn manually – which would be a good way to ‘earn’ calories to swap for ice cream!).
The first features a liquid (essentially anti-freeze) filled bowl that needs to be frozen down 12 or so hours in advance before placing it into the churn, swtiching on and adding your ice cream mixture. These are comparatively inexpensive machines, they work really well for a single batch of ice cream and they are simple to operate. The only disadvantage is that you will need to remember to freeze your bowl in advance of your ice cream session (or you could keep it there at the ready all the time) and you will generally only be able to churn one batch before the container needs refreezing. These are really good starter models if you want to give home made ice cream a try before committing to a compressor model.
If you decide that ice cream really is your passion and you want (or need!) to make batch after batch, then consider a compressor version. These feature an actual compressor so your ice cream maker is effectively a freezer unit. You just turn it on, wait until the chamber has cooled right down (on my Magimix Professional that’s about 10 mins) and tip in your mixture and the machine takes care of the rest. These machines definitely have a larger footprint and a higher price tag but to the true ice cream devotee, they are an investment to consider.
Also available to those who have a KitchenAid stand mixer is their ice cream bowl attachment which is a freezable bowl that fits only your machine. They work on the same principle as the ‘bowl in the freezer’ model above and don’t take as much storage space. And, finally, and most recently on the market, we have the new Cuisinart Fruit Scoop which answers the 'healthy dessert dilemma. This machines, which also doubles as a conventional ice cream machine, has a special four pronged churning blade which chops and purees fresh fruit whilst simultaneously freezing it. The result: soft, scoopable, real fruit 'ice cream'. We have trialled these extensively and are very impressed - whilst it's not technically ice cream, it's still a sweet, creamy textured frozen dessert that allows you to indulge a little more frequently, and get your 5+ a day!