Here are two I made from 1" dowel pieces.
The larger screw eye on the end works great if you hold the tip of the shaft on a table with the shaft slid through the eye and pull and burnish the high spit in the shaft. Looking down the shaft and twirling it repeatedly (or roll it across a table) to check for straightness. The grooves work best for "kinked" shafts. I fitted one th 23/64" and the other to 11/32". The hole works, topo, but not one you need to get to the fletched section (rarely a problem if you straighte twice before fletching).
A round screwdriver shaft works well also. This isn't rocket surgery.