Remember, I'm not an experienced plug maker but sometimes I run across ideas while doing other projects. I'll pass along what I've done and then let you figure out if it works or not.

One time, when sanding a rounded part, we got a long dowel type piece that fit in the lathe. This dowel had sand paper on it. As the lathe turns, you just rub your piece up against it. Might work for the lip. I don't remember if the sanding piece was storebought or home made.

Also, how do you guys feel about duplicators?

I need one...but it's 300 bucks for my lathe... I love you Santa
I know he's listening :)

Duplicators are nice, I am one :D

Once you get yourself set up you can crank stuff out pretty fast. I spend more time setting up than I do shaping most of the time.