Yesterday I discovered that toothpicks fit my drafting pencil and should work as a "pointed dowel", although I don't have anything to test it on at the moment. American made toothpicks have traditionally been made of yellow poplar, a hardwood with some substance to it. I have some asian made toothpicks I bought recently that are way too soft. The triple size fiberglass pen I ordered from Amazon has been discontinued, so no fiberglass pen. Travelling down that same train of thought, with a hammer, I smashed an old carbon fiber tent pole and also an old broken fiberglass fishing pole into usable sizes to fit into the drafting pencil. I broke them to length with a vise. Some modifications like sanding, filing, or grinding will surely be needed to the ends to make them suitable to the tasks you need them to do. I suspect I have cost pen makers a bit of money with this post.