I teach a (home sewing) class where the students make their own personal fitting shell (I call it a sloper) and then I teach them how to use it to evaluate and adjust commercial patterns. It lets them see how their waist length differs, where their bust point is and to rotate the darts to their bust point, adjust the shoulder slope etc. This corrects all the major glaring problems with the commercial patterns (which are horribly drafted, there are so many mistakes in them when you stop to check them its amazing!). I let the students know there will still be some minor fitting to be done.

I use the draft from Harriet Pepins’ “Modern Pattern Design” from 1942. The book can be found in its entirety at http://www.vintagesewing.info. but I teach them to measure based on the instructions in the book “European Cut” – building the bridge between the breast and measuring over that.

So this is one use for the ‘personal fitting shell’ My students are amazed at how different their bodies are from the patterns.
Judy