there are also 3 short bras in the flipper arm
Must be pretty robust undies to weigh 3Kg :shock:

But depending upon the forces in the pivot I'd say either use steel pipe (seamless or welded, makes little difference) or ally bar. I'd hazard a guess that nylon wouldn't last very long before it shears or gets cut up badly.

If weight is a problem how about using some bolts/setpins instead of a full length of bar? Or as an alternative get your existing bar bored up the center by a friendly machine shop?

Just a thought.