This is why we modify things like spinners. Find one that is the sort of shape you want and then enlarge the hole to suit and modify the blade slots to suit the hub of the folder. Avoid sharp corners and ensure that the clearance is a hair larger than needed so the spinner plastic or metal does not make contact with the actual hub.

If enlarging the hole for the shaft requires drilling out the hole use the trick for modifying a drill bit for brass and plastics so it doesn't grab and cut an off center hole. Keep these modified bits for future brass and plastics drilling. They are VERY handy. If you've never done this trick to a drill bit you'll be shocked by how well it works and the degree of control you get with this.

https://www.youtube.com/watch?v=pAngKHIZgyA