Polished stainless steel mirror. Reflected light can be seen for many kilometres. 72mm x 97mm.
Remove protective plastic cover to expose the highly reflective surface. Extend one arm and use your thumb as if it were a rifle sight and line it up with the object that you want to attract. Place the mirror near your eye and angle it so that the sun’s reflection flashes across the thumb towards the object (in this illustration the plane).
If the object is moving, rotate your body to keep the thumb aligned with the object. It is much more effective to keep the mirror flashing across your thumb rather than holding it static.