Here is quite a different approach of taking an out-of-the-box form and adjusting it to your own measurements or your liking.
Lauren Reeser has her way (really!) with Lilly, and goes to town about adjusting some of her features…
I posted part of the article here. the rest is on her web page, which is an incredibly good source for anyone, who is into historical costuming!
Making a Workable Dress Form - or - The Violent Transformation of Franken-Lilly
This is Lilly straight out of the box.
Lilly is a dress display mannequin, as opposed to a dressmaker’s form. She has a nice jersey cover over a molded, hard foam body. She has removable arms that can be posed. Her measurements are B34-W25-H35.
LIES. She has CRAZY boobs, and a weird square waist about 26” around.
The original idea with Lilly is that I could stuff some cotton batting around her waist to help achieve my waist circumference, but also length. This didn’t work at all.
Lilly’s problem is that she’s just too busty. She’s a 34” yeah, but not at all like MY 34”. She also had some funny square-ish-ness to her waist. As you can see, the stays don’t work on her.
Solution to Lilly’s problems? A dress form mastectomy.
These are actually more common than it may seem, and often happens to Uniquely You dress forms. In Lilly’s case, I was able to pull down the jersey cover and saw away her body with a sheet rock knife. A large bastard file and some rough-grit sandpaper helped smooth things out.
…Please read on via the web page…
American Duchess:Historical Costuming: Making a Workable Dress Form - or - The Violent Transformation of Franken-Lilly | Historical Costuming and sewing of Rococo 18th century clothing, 16th century through 20th century, by designer Lauren Reeser