In 2004 Team 1114 used carbon fiber tubing for our gripper.
http://www.firstrobotics.uwaterloo.c...rms/arms83.jpg
It wasn't called for in our initial design, but after a couple iterations, we soon realized that weight was a huge issue for our team. We needed a lightweight gripper to ensure we fell within the weight limit, and to lower our center of gravity.
The carbon fiber tubing solved our weight problem, but we quickly realized that it wasn't going to be rugged enough to last for many matches. Knowing this, we designed the gripper so that individual portions of carbon tubing could be swapped out very quickly. This modular design allowed us to deal with the frequent breaks. (IIRC, a certain college team from somewhere in NY state snapped our gripper during a practice match...
)
So, if you're going to use carbon fiber tubing, consider filling the tube with some sort of structural support, and be prepared with spares.
We ordered our tubing from
Aerospace Composite Products. They have a variety of thickness, diameters and lengths when it comes to
tubes. I believe we ordered the 60" sections. They shipped to us overnight (yes, across the border!), and were a pleasure to deal with.