In addition to all of the above, OH used to put the angle grinder on a concrete block whilst ours were being fed in the yard
We also used to take one each and walk down to the main road (in arms) to watch the traffic go by, lorries, cars, buses and a fire engine in full response mode with one litter :-D they were bomb-proof :-D
It can backfire somewhat, the pup I kept from my first litter thought that a pneumatic drill being used as we walked past was an invitation to play ! LOL