I've got a local teenager who I am teaching to turn pens and such. He is a good kid, a little slow, but he tries hard to learn what I am showing him.
Today when school was out he came by and said he had been in the woods with a buddy and their bb guns. He said he found a small stand of bamboo that was different from any other around it. He came back, got his dad's limb cutter and went back to harvest some for me. He wanted to see if this was like what I was wanting for pens.
Take a look at some of what he brought me.......
It all is the right diameter for either 7 mm or 10 mm tubes and the joints are as close as 3/4". Gonna try one tomorrow and will let you know how it comes out. Just when I was gonna buy some of that expensive pipe stem bamboo ($25 for a 15" stick). I may harvest some of this to sell if there is some interest. Let me know if you want some at like $3 a blank (plus postage, of course!)