We're going to talk about dress-forms... and fixing yours so it fits you. That means you're going to stare at a fake torso wearing lingerie... and I'm going to talk about lingerie and torso shape, in detail. If that's not for your eyes, or someone around you shouldn't see that, click away. Betsy is normally properly dressed - but not today.
I call my dress-form Betsy. Like most off-the-rack dress forms, Betsy is a small B-cup with no abdominal fat. That's fine. I'm sure we'd all like to look more like Betsy. (With less pillow-fluff leftovers, lol).
However, the point of having a dress form is that it is more-or-less your shape and size. I can't quite get her padded out perfectly without doing a lot more work than I'm willing to - but I need to do something.
So I use bras, bandages, and pillow fluff. Oh, and a tank-top to keep her decent. ;)
Betsy was due for an upgrade, she's been the same size for some years, and I'm no longer that size. The bra especially had to go.
And when I remeasured me, and then remeasured her... some of the ab fluff went too. (That is always cheering.)
This time I used a bra that I bought about a year ago - the last bra I bought. It fits my breasts ***perfectly*** - and I found out the first time that I wore it, it digs into my sternum and makes me miserable. I've worn it a few times with a cotton ball stuffed between the wires and my skin, but that's not nice, so it mostly sits in my drawer. But - if I want something that nails my current form? Hm... better than not getting used anyway.
So Betsy got restuffed (the stuffing comes up a bit over the cups because so do I. Usually she wears a tank-top on top.
My method is to measure all the usual suspects - B/W/H, and then back-width, front width, distance from shoulder to bust apex, distance from apex to apex, distance from sternum to waist, abdominal measure (different than hip measure, especially if you're fluffy there). I adjust Betsy as much as possible, then stuff her with pillow fluff to make up the difference.
And then I put the tank-top back on because I find having a mannequin wearing lingerie staring at me while I'm trying to sew somewhat offputting. And my neighbor can see into my patio, so that's sort of embarrassing.
This method is way easier and faster than you'll find out in the wilds, and it works well enough. Gives a good first fit for my sewing, even if I have to final-fit on my real body. But that's normal.
I'm working on re designing the next corset (see ALU if interested) so I am using Betsy to mock up some pattern changes. I don't use her nearly as much as non-sewists seem to think, but she's handy. :)
Hope this helped (or amused) someone out there!