This is so easy to make, so I'm offering up this pattern for free:
I used two balls of Red Heart "Heart and Sole" in Razzle Dazzle with two strands held together.
Using size 3 needles, cast on 26 stitches and join in the round. I used magic loop, but you can use DPN's if you like that better.
K1, P1 for about eight rounds, or until you have 1 inch of ribbing.
Switch to size 6 needles and knit straight for 25 inches more (total 26 inches).
Switch to size 3 needles and K1, P1 the same number of rounds you did in the beginning.
Finished Length: 27 inches
Finished Width (diameter): 4 1/3 inches around
You can substitute any yarn you like. My gauge for this project was 6 st/inch. Note: this was for a Canon Rebel - I don't know if all camera brands have the same dimensions. Double check your measurements to be sure.