Huge thanks for keeping this library going, Eric - the rusty metal set is exactly the kind of thing that saves a weekend when you are blocking out an industrial map and need something better than flat grey dev textures to judge silhouettes and lighting.
Since a few people in this thread asked about filling gaps while they wait for the right free photo, here is the workflow that has worked for me on the last couple of layouts. I keep two separate buckets: shipping assets, which stay CC/attribution-clean from libraries like Soundimage, and pre-production material, which never leaves the whitebox stage. For that second bucket I generate concept frames and moodboards with an ai image generator ( https://soralum.com/image-ai/image-generator ) - prompt in the mood, the era, the light direction and the material story of a room, get half a dozen frames, then pin the two that read best next to the BSP in the reference viewer. It is much faster than hunting for a photo that only half matches the space you already blocked out, and it forces you to describe the scene in words first, which usually exposes the fact that the layout has no clear focal point yet.
Two caveats worth repeating for anyone new to mapping: generated frames are direction, not shippable art, so never bake them straight into a texture set you plan to release, and always keep the licence trail of the real assets you ship. Used that way the two sources complement each other - free photo libraries for the trim sheets and decals that end up in the map, generated boards for the mood pass that tells you which corridor deserves the expensive lighting. Thanks again for the constant updates, the metal pack is going straight into my reference folder.