Terry,
The boy's at OB Cues do take car of their customers and there should be no need to make any custom to him.
He would most likely get a free fix from them without any problems.
If however the customer don't want the stock ferrule, he should be aware of that he is leaving "the safety zone" area and is on his own.
The ferrule is extremely light and finding something else which don't change the way the shaft plays is a puzzle you need to sort out.
The new ferrule needs to be capped for sure, if not you need to get the stock fiber pad from OB Cues to glue on
top of which ever material you make you're ferrule of.
If you don't manage to convince the customer, give Royce a call and discuss a potential combination.
I'm currently investigating this topic my self for customers which wet their pants when they don't have the magic "CLACK" sound they are so used to from their other shafts.
The idea is to make something in the lines of you're customers needs, but I would for sure be experimenting with my own shaft which is out of any warranty discussions.
I have made some pictures for you if you feel this is something you would like to get you're hands dirty on,
but as mentioned the customer is on it's own.
The OB shaft has a tenon but the walls are not to thick. It has therefor a stronger wood inside it's core to strengthen the shaft.
I live any further details to you to discuss with Royce at OB Cues.
Hope it helps.
N
