I was hiking in switzerland with some friends when we found this thing.
After some googling, I found that it was the rocket motor on a Raketenrohr-80, a Swiss recoilless anti-tank weapon (the gold tube).
I managed to get it back to the UK. I then bought and gutted a desk lamp from a charity shop; I put the light fixture in the top, inset the switch between two of the fins, and ran the cabling through the centre.
Now it lives on my desk