I've done many TTS shrink fit holders. I did them in stainless.
Here's how I did it:
1-start with a 1-1/2 stainless shaft.
2-on a lathe, make the 3/4" shank and the TTS shape (with the groove, ...) the fit in the spindle end, OR buy the TTS machinable blank.
3-on the lathe, make the shape of the other side of your holder. ie: for my 3/16" shrink fit holder, I started with 1" and taper it down to 1/2".
4-Put your holder in the spindle of your Tormach and do a reverse lathe(lathe on mill). If you make a search on this forum, you'll find some info on this. You'll drill a hole in your holder then finish it with a boring bar. I've done 1/8" shrink fit holder with a micro boring bar with no more than .0005" run out. That's the hardest part...