Art,
I would think that plastic rod would work great and you wouldn't have to worry about moisture transfer. It might be a bit more expensive than wood. I used 1 1/4" Oak dowel from Home Depot, cut in 5 1/4" sections. I turned down the top 2 1/2" inches to 1.16" (about 1 5/32") so it would fit inside the tool head.
Ron,
Sorry, I apologize.
But Ron, your a Master, and I'm a lowly Expert.....and you have your distinguished badge too. Talk about showin off!!