I printed in white ASA because that is what I had on the printer. Works fine. I suspect black in PA or a variant would look more “traditional” and be more durable. It works with the O-Rings (they are #9 if you need to buy them from the hardware store). I have springs on order – they should work too.
On-Shape model for this and other ILCA parts is here: https://cad.onshape.com/documents/080a8b0994a661a98dea68e9/w/e814f5fa87d997a3b6ccba1c/e/f5e4782fb9d5817faca88c69?renderMode=0&uiState=68a361531c0b6f220f30e3ea
The author marked this model as their own original creation.