Go customs makes a carbon snooker shaft that's 9.5mm and a pool shaft thats11.1mm, not sure if you would consider them production shaft though 🤷🏼♂️
Cuetech cynergy comes in a 10.5mm size.
https://youtube.com/@Mikex73
I've been getting these 2 recommended to me for awhile now and was gonna post asking which is legitimate but kept chickening out. Interestingly they have almost the same videos.
Pool players are quite the crafty bunch. I'm sure one of you could hook a pocket chalker to one of these badge leash deals. Would never lose a piece of chalk again! Although now that I'm thinking of it, someone would probably steal it out of jealousy.