wow I had never heard of this before: Eltro Information Rate Changer was a real-time tape-based device, with separate control of pitch & duration, from the 1960s!

Great news: Paulstretch has a new developer!
New version here (incl iOS beta)
https://sonosaurus.com/paulxstretch/

“This application/plugin is based on the PaulStretch algorithm (Paul’s Extreme Time Stretch, originally developed by Nasca Octavian Paul), and specifically the PaulXStretch version from Xenakios. The UI has been updated, adapted for various screen sizes, and built for the latest platforms.”

A useful reference from 1722 for my Bell Piano project:

via Filippo Buonanni’s Harmonic Cabinet (1722)