This would be mighty complex, but I think it might be possible. Here's how I think the process might go down:
- Make your After Effects project, importing some placeholder images. Save the project.
- Client uploads images. Those images need to be converted to the same image filetype (PNG, JPEG, TIFF, whatever) as your placeholder images, renamed to the same name as your placeholder images, and placed in the same directory as the placeholder images that were referenced in your After Effects project.
- Run After Effects from the command line using aerender. More info on that here.
- Render to a public directory and give the link to the client.
- Delete the client's uploaded images to make room for the next client.
Heres where things would get tricky:
- I don't think it's feasible to edit the After Effects project file, so I think the client would be limited to the exact number of images you made in your template. Any more would not appear in the rendered movie, and any less would give a media offline error. I do not think it is possible to have After Effects import media via a script.