Dave Paine
i made an insert for my drill press, since I did not like the large hole in the original. I seemed to miss holding the bits when I unscrewed the chuck and they fell through. For the small diameter about 2in this did not take long.

I think you will find that you do not need a set of inserts. I most frequently use the 2 1/8in ring. Most space for the dust collector's air. I have only a couple of bits which are larger than this ring. I just want a ring which will give adequate clearance for the bit and allow good airflow. The benefit of wood or phenolic is to minimize risk is a bit did touch the ring. Too easy to raise a large bit more than anticipated. I have experienced this with my sacrificial adjustable fence. Made the gap a little too narrow for the bit. Since it is made of MDF, no damage to the bits.

After reading this, I decided to give a try to turning a ring. It will not lock, but I am not expecting the locking action is necessary. I found a piece of scrap walnut which should have a stable grain pattern.

I will report back on whether this works out. At present the piece has been rounded and faced off. Now to turn to correct diameter and carefully cut for the 1/16in thick flange to hold in place.

A big unknown will be whether this warps over time. I do have a phenolic sheet I purchased to make a router plate if this does not work out. I never did use this since I purchased a lift which had an aluminum plate.