I actually used 2 axe handles for the wood, those diy shops seem to only sell spruce in usable sizes, I'm not sure what kind of wood this is, probbably ash or hickory.
For the pins i used 5mm galvanised bolts with wing nuts on both sides.
The tensioner is actually slightly s shaped and if positioned correctly it wil fit around the main brace.
I did not realy use a finish on the wood, just a quick whipe with sunflower oil.