Stereo 3D Toolkit 3 is a set of stereoscopic workflow tools for After Effects, built by Ryan Cashman and distributed through aescripts. It manages true left and right channel hierarchies and lets you convert any pre-comp into a Stereo 3D pre-comp, so stereoscopic compositions can be assembled inside After Effects.
The toolkit is compatible with 3D effects and plug-ins and works with your favorite plug-ins. It also accepts camera footage and renders from external 3D software packages, and it supports multiple Stereo 3D workflows in a single project. Version 3.0, released July 6, 2022, is described as a cleaner and lighter version of the classic Stereo 3D Toolkit, compatible with After Effects 2022 as well as 2021 and 2020.
A demo video is available, and the developer's page on aescripts carries the download and current compatibility notes.