Does your friend use up batteries after being in toys for children?
I have a flashlight Malkoff 1AA, it is very economical and was able to drain the AA battery to 0,6V, after a while the battery is restored, when the battery recovers above 0.8V, it works, when the battery recovers after 0.6V to 0.8V or less - it does not ignite. He was able to use the battery for 2 hours, who could no longer move the hand of the table alarm.
The best thing in my opinion is to find an adapter for 3 * AA in flashlight body for 3R12 battery
and use the diode and guts from this lantern for a 1.5 volt battery, for example from inova microlight, or
https://laughingrabbitinc.com/index.html
Then your friend will get some number of photons from dead batteries
as a case for such a Frankenstein, you can use a German military flashlight
But, what is important here, you will have to use only dead batteries, if he installs fresh batteries in a similar structure, he will be able to kill the diode, or maybe not, I have not tested it yet