Able to make large amounts of tasty cold brewed coffee at a time, the $40 Filtron Cold Water Coffee Brewer doesn't demand much of an up front investment either (the price roughly converts to £30 in the UK and AU$55 in Australia). The manual contraption is a bit tricky to operate though due to its big size and more parts than its competitors.
Similar to other cool water brewers such as the Toddy and Oxo systems, the Filtron is essentially a plastic, cylindrical bucket (called the "coffee bowl") that holds coffee grounds and water for steeping, which you then place on top of a container for decanting. Like those other products, you also must plug a tiny hole on the bottom of the coffee bowl with a rubber stopper.
Where the Filtron differs though is its use of a second "water bowl" designed to trickle brewing liquid over its supply of coffee grounds. The water bowl has no stopper for its small bottom opening so your finger is required. That's three main sections in all, two of which you perch rather precariously on top of a very slender plastic carafe. Perhaps that's why the vessel is plastic as opposed to fragile glass which the Oxo and Toddy products use. It feels as if one stray nudge could tip over the entire set up.
The Filtron does offer two filtration methods, either reusable felt pads or disposable paper filters. While it's not as easy to clean as the Oxo Cold Brew's metal or small paper filters, the Filtron does provide more flexibility than the Toddy which uses felt pads only.
After brewing overnight (16 ounces, 453.6 g coffee -- 64 ounces, 1.9 L water), pulling the rubber stopper causes fresh cold brew to drain into the carafe. About a 25 to 30 minute process, I netted a sizable 36 ounces (1.1 L) of rich, delicious coffee concentrate with a high TDS (Total Dissolved Solids) percentage of 4.6 percent.
The quality of its output should put the Filtron on your cold brewer short list. That said, if you don't mind making less in one batch I suggest spending $10 more on the $50 Oxo Cold Brew. For a simpler device capable of the same quality and quantity then go for the $40 Toddy system.