[MetalJacket]

We've actually used this stuff quite a bit in the past (although we don't tend to use the finned tube on robots - more on organizational stuff). If you look at the claw on this robot, you can see some of the nylon connectors being used. If you use the ridged tubing that they sell, you can actually get a pretty strong connection without pinning it (although just to be safe you might want to anyway) but you can use the connectors with almost any 1x1 tube if you do pin it in place

EDIT - To be more exact, we use connectors from Esto but it's the same concept