There are many different types of worm bins. You can make your own from just about anything to start out with. A 5 gallon bucket will work just to see if you like worm farming, of course if using a 5 gallon bucket you will not need as many worms to start with. If you start small and see that you are enjoying taking care of your “herd” then by all means go bigger. Maybe your test will show you that this hobby is not for you. But, you will never know until you try.
The picture to the right shows two continuous flow through type bins (CFT). With these bins you feed on the top and harvest castings from the bottom. Usually there are no worms in the finished castings from the bottom.