As the saying goes "practice makes perfect."
That rings true for many aspects of life from learning to ride a bike to computer coding, and it's certainly true when refining your fly casting technique. Fly casting does require a fair amount of open space for any decent practice session with a typical rod, but some folks simply don't have that immediately accessible. Another is the weather—if it's blowing 40 outside or dumping snow, chances are taking a nap or maybe tying some flies is far more attractive. Thankfully, your fly casting practice doesn't have to be put on the back burner when the mood arises.
Tiny "practice" fly rods allow you to, well, practice fly casting techniques with a minimum of space.
Yes, you can definitely use them indoors. These are extremely short rods that have actual fly line or something like a length of yarn to simulate fly line (BEWARE if you have cats around!). Quite a while back, I reviewed one of these little sticks from our friends at Redington right here.
Absolutely nothing beats casting with a real fly rod in an open outdoors space, but these micro rods do provide some real value. No, they aren't made for actual fishing or for casting with much distance, but they are a good secondary tool to use for helping to refine casting mechanics.
With a micro practice rod you can work on things like your timing, loop control, and backhanded presentations. Since the rod and length of line is so short and everything is happening so close, you're able to be very "connected" to the cast which makes it easier to correct mistakes or quickly try different things to see what the immediate effect is. It's fly casting on a much, much smaller scale.
Two of my favorite uses for my micro rod include practicing direction changes and especially accuracy. You can also use one for some friendly competition among buddies. Try casting at small targets from different distances, toss in some obstacles and various angles—make a contest out of it. Practice doesn't have to be lonely and dull!
Should you get one? Well, it certainly can't hurt, especially if you have limited space to practice with a normal fly rod or live where the weather is nasty half the year. Whether it's mid-winter or the heart of fishing season, you can never practice too much anyway!
The three practice rods I'm familiar with include...
Redington Form Game Rod
ECHO Micro Practice Rod