Like Al Hockenbery, I made my chucks using PVC pipe couplers (3”, 4” and 6”). However, instead dedicating a faceplate to each chuck, I made a combined chuck and slotted retainer for the PVC coupler from scrap 0.5 inch (obtained free from a local bathroom installer). I laminated 2 to 3 layers of Corian using epoxy, and then I bored and tapped a hole to fit my headstock. Then, I mounted the result on the headstock and turned the base to final shape and cut a circular slot in the disk to accommodate the PVC coupler.
Rather than truing up the outside end of the PVC coupler directly, I turned a ring from Corian and slotted it to fit the coupler, glued it on, and trued up the result. I used a ring of rubber material intended for patching wet suits as a seal on the outer end of the chuck, but several alternatives exist.
The major expense was the tap to match the headstock spindle of my lathe
By the way, I have found scrap Corian useful for many tools, jigs, etc in my shop. It is stable, strong, and machinable.