I've done the drap the shirt-in-process-in-front-of-a-mirror thing, and found it to be time consuming and more than a bit of pain
Male tailors dummies are hard to find, new or used, and are quite pricey to boot. I've checked out "body casting", various DIY tailors dummy applications, duct tape and everything else I could find. None looked to be particually good for my needs.
Then I wondered, "What if I just used ordinary stiff wire to make a "hanger" the width and slope of my shoulders, and the width and height and slope of my torso?", a two-dimensional dummy of the shirt I want to end up with, rather than a three-dimensional dummy of my body.
I have Wild Ginger software to make a sloper, or I could use a current shirt I like the fit of.
What's say? Anybody ever use something similar to effect? It certainly would be cheap and quick to make.
TIA