I have designed it for one size and need to modify my design to be able to use the same holder to hold the different size cylinders, need to be from 20mm to 50mm in diameter.
You can use a three jaw vice similar to chuck post on a lathe. For self centering you can add a mechanism similar to chuck on a drill machine.
Message me if further help or model is required.
Thanks for your help, but need something to adjust easier as it is a plastic tube holder and news to design it in way that can hold different size!