Okay, turned up one endcap, and filmed parts two and three. One more endcap to make tomorrow for the other end of the cylinder- I'm showing two ways of turning the endcaps, one with a mandrel, the other without a mandrel but using friction to grip the parts, which means you don't have to drill a hole through the middle of the endcap to hold it in the lathe.
The endcap pictured was cut from from 15mm PVC sheet, turned in the lathe, and fits a 68mm PVC cylinder. Took about half an hour to make the cap. Takes a lot longer to talk about and film making it, than to actually make it.