I build them by cutting three seperate rings, and using CA glue to make them 1. There is also a lip that its sitting on in the picture, this is made using the above method posted and multiple saw bits. You really have to watch your depth as you cut so as not to cut through the lip, its less than 1/8".
Its left with a rough edge so that after the mid driver is glassed in and the shape of the pod established you can use the hole saw to cut the appropriate size to slide the cup into. The rough edges grab the fiber glass mat that will be used to mount the tweet cups into the form better than a smooth edge does.
MECP 1ST CLASS
FF08 FASTEST OVERALL TRACK TIME