you could try to file down a small dowel, then stain and finish. I think you'd get more consistency with this then say wood dust and epoxy. Although the wood dust and epoxy would definatly be easier and I am sure they are small holes. You could look at some canoe building sites on how to do this. I am sure 60 minute epoxy would work. You could do some test runs with some wood dust to try and get the right color. Let it set up and see how it turns out before doing it on your bow as it is quite permanent.