@pebble@critters.gay If you have access to a Linux/Unix box, here's a lightly modified version of the bash script I use for this: https://smallcrow.com/gallery.sh

It requires imagemagick, and png source files. The gallery is in alphabetical order, so name files accordingly.

UPDATE: Here's a version that supports both png and jpg sources, and uses reverse order: https://smallcrow.com/gallery2.sh