Paint/Animation app PDHowler 2020 free through July 2021
First I wanna thank @Stargazer54 for turning me on to PDHowler several years ago. Great recommendation.
PDHowler is a unique photo/animation program developed by Dan Ritchie. PDHowler has a power suite of image editing tools and utilities for animation, including a fantastic motion estimation module (Twixtor-like frame interpolation for artificial slow motion) and some 3D modules, including landscape tools that can export OBJ for use in other software, and a raytracing module for 3D renders in Howler itself.
Version 2022 is now shipping, but Howler 2020 is currently free for a limited time. I'm all about using all kinds of different tools and Howler is a good one to have.
Just for fun here's a set of animations done in PDHowler with the "Puppy Ray" raytracing engine.
And here's the tutorial where I found out PDHowler 2020 is currently free. This part 1 doesn't actually get into the Motion Estimation to slow down the animation - this is all about creating the animation, which will be slowed in the future pt 2, but it'll show some of the features of the software nicely, along with its unique workflow.