I'm not entirely sure but i'm assuming this is to make the flash brighter.....it's interesting anyways
and statement: smoking is bad, ok hehehe
[ This attachment cannot be displayed inline in 'Print Page' view ]
Materials:
SLR with built in flash
Cigarette packet
pocket knife
Instructions:
Remove the foil from inside the pack, taking care not to tear it. Once the foil is removed, reverse it so the shiny side is facing inwards. Then reinsert the reversed foil into the packet. This provide a reflective surface to bounce the light out of the box.
Note: With some brands of cigarettes, you can skip this step as the foil is already facing shiny side in.
Attach to camera. Feel free to adjust the angle of the packet's lid, to differ the angle of the flash spread. Also, experiment with position of the box. Reversing the box may also help.
In no way will this replace a $400 external flash unit, but it is improvement on what you already have using something that you can probably find on the floor the next time your at a pub.
source: Cigarette Packet Flash Diffuser : 5 Steps (with Pictures) - Instructables (https://www.instructables.com/Cigarette-Packet-Flash-Diffuser/)