During one of our early stops at Mrs Rams brother’s house, I noticed he had a shiny disk on the wall. It was from the inside of a computer hard drive.
Just a few days later in Columbia, PA, I saw something similar on a shelf at the Tollbooth Antique Marketplace. It was shiny mirror with these instructions on the back.
This mirror, manufactured by General Electric, was issued to soldiers during WW2 for emergency signaling aircraft or ships.
Backpackers will often carry a mirror like this for emergencies too. However rather than spend $10 for one, you could ask you family tech guy for a disk from an old hard drive.