Right, I just mentioned that in another comment. I’m not quite sure it would count under OPs restrictions:
The only pattern/material that comes close to what OP is looking for would be a parabolic mirror. If you attach one of these to your shirts and then stand at the exact right angle and distance to a camera, you could damage it. However that is already stretching “passive” because it would require a lot of deliberate actions to position yourself that way. And it pretty much only works when the sun is out.
remon@ani.social 2 days ago
Right, I just mentioned that in another comment. I’m not quite sure it would count under OPs restrictions: