On Thu, 14 Dec 2017 19:23:37 +0100, Emanuel Berg
wrote:

Once there was a guy who had a bounce free
hammer and I asked how it worked. He explained
the little balls going up and down. I was
terribly impressed by this. But then one day
I used one myself and slammed it open and could
see it all first hand. It was still a good
answer but quite possibly that's the way he had
found out as well. Somehow took the magic out
of it.

Perhaps you are thinking of a "dead blow hammer"?
https://en.wikipedia.org/wiki/Dead_blow_hammer
https://www.google.com/search?q=dead+blow+hammer&tbm=isch
The good ones are full of tiny steel balls. The cheap junk uses sand.

"Learn by Destroying(tm)" also means that you really don't understand
how something works until you've broken it, taken it apart, and fixed
it. I've learned more from things I've broken than from playing with
the pretty knobs, reading the instructions, or using it for its
intended purpose.



--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558