PT3D is a helper for stitching stereo photos. It works by converting a PTGui project into a new project, with adjusted control points that allow aggressive warp-to-fit without spoiling stereo registration. It has been in use on Windows and OSX since August 2016. Somewhat to my surprise, it keeps getting better.
Version 1.4 is a pro-quality tool that produces good-to-excellent stereo stitches in most cases, and requires a minimum of labor. Not a small minimum — stereo stitching still takes 2 – 3 times as much work as 2D stitching — but small enough to make commercial use feasible. And it comes with a comprehensive user manual full of helpful tips on stereo technique.
PT3D is licensed to registered customers of Panini-Pro.com on a per-seat, per-year basis. One seat for one year costs $90 and there are generous discounts for more seats or longer periods. New customers get a fully functional 30 day, 2-seat trial license.
Go to http://panini-pro.com/PT3D/ to download for Mac or Windows, register and buy a license.