I was watching another Roy Underhill video where he showed us making a Shaker round stand. He explains the original table was built by the Shakers and how he has been wanting to replicate one. He discussed this specific tables perfection and harmony when it came to the shafts contours into the legs and the overall design.
Image from inside The Woodwright's Shop
He was ecstatic to come across a lathe template for this particular table in his travels and show it to us in the episode.
Image from inside The Woodwright's Shop
My issue was that he didn't really show us how he used the template while he was using the lathe.
In its simplest form I suppose you hold the template beneath the work piece while it is mounted on the lathe and eyeball where the changes need to be made. Then turn on the lathe and work while periodically checking the template.
I feel that could be an error prone approach.
So, that being said, how do you effectively use a 2 dimensional template, like the one Roy shows above, when turning?