Display MoreRossi was probably using in his hand-made samples a simple high-power LED on chip, e.g. like this
The circular LED can be seen in the dark background on the images in Levi's report. Could be Rossi simply disassembled a flashlight to use the LED chip...?
I'd rather say he just put the whole flashlight into the white tube. We can also see the quite typical bulky lens of those flashlights.
Below is just one example, there are many more on Ali-Express. See the yellowish halo around the spot on the pictures. He probably fatally believed the "10.000 lumens", our Chinese friends are notoriously optimistic about the output of their flashlights.
3.58US $ 16% OFF|10000 Lums XP L V6 L2 LED Taktische Taschenlampe Led Taschenlampe Zoom LED Taschenlampe Wasserdichte Taschenlampe Licht Für AAA 18650 Wiederaufladbare|LED Flashlights| - AliExpress
Smarter Shopping, Better Living! Aliexpress.com
de.aliexpress.com