It's a small interesting piece, that gives you spectacular results, shame that is only available for the Diana F+ and the LC-A cameras. In fact, you can create one in no time and without having to search everywhere for suitable materials for it. Because it's provided by Lomography! Here's how...
When you bought your beautiful Sprocket Rocket you’ve probably noticed that inside the box, the camera was stuck in a plastic bag of the same shape. Well, that piece of plastic is a good starting point to create the perfect Splitzer.
Cut that plastic cylinder up to about 1 centimeter and draw the line that divides it in half. With a small pair of scissors (for the nails is perfect) and trim off one half until you get the circumference of the circle.
Now try to insert the Splitzer incomplete and possibly cut off the excess until it will fit (mine is slightly less than 1 cm).
With a black electrical tape cover the other half by fixing all the pieces with a single piece all around, finally cut off the excess.
I bet that now, even if you don’t have a Sprocket Rocket, you’re looking inside the packaging of other Lomography cameras… Yes, you can use the same method for other cameras!
Below some of my results: