Bimanual activities that require a prosthetic arm (one with industrial qualities) often times evade the prosthetist, the societal arm chair citizen, the academic researchers, the media makers that "use" amputees as stereotypes, in many aspects - one risks to overlook the simple glory, the sunshine that goes with doing it, the hardness of it, the pride. And the fact that it requires putting one's mind to something that is not just as self understood as it may appear.
What seems to be never considered is the fact that I really need a prosthetic arm for actual bimanual activities. It is for these situations where there is a need to work two-handedly, where a prosthetic arm attains a deeper relevance and importance. And it is not just me, that as a need there, actually. That is the type of stuff one generally needs a prosthetic arm for. Those activities are the ones where insurances usually tend to agree to pay for a prosthetic arm - a prosthetic arm that works through these tasks, mind you: hard work, repetitive work, two hands required, very hot, very cold, dangerous. Leaving the amputee totally intact, by the way.
Operating a hedge cutter is just not possible, safe, or easy with just one hand. In other words, we talk about real work. And no, you cannot "just put your mind to it". Sure with a small tiny clipper you can approximate the sound and feel - but with 2-3 kg and overhead work with a long powerful cutter, one-handed is a big risk, and operating the switch together with directing the blade is very hard.
That, as opposed to drinking coffee, reading news paper, just going for lunch with a food tray, cutting pizza or meat, shopping with bags or baskets, tying shoe laces, talk past a Bialetti when making remarks about "making coffee", opening a fridge, wearing correctly sized trousers, walking a dog, drinking alcohol, or such - all of these work with a Becker hand, with a passive arm, with a hook or without prosthesis quite well, too.
Not, like, hedge cutting. This requires, like, a real prosthetic arm. It cannot be done without prosthetic arm, with a passive arm, with the "bionic" stuff (their control paradigm is just not safe for that type of work), certainly not with "3d printed" gadgetry that risks to scratch up your stump in no time. I talk about reliability, comfort, overuse, asymmetry, grip function, the stuff that hopefully, my real sustainable living future is made of.
To show what is required, or done, with a prosthetic arm in 2015, I cut the outer and inner perimeter of my hedges in the early afternoon of what turned out to be the hottest day in July in Switzerland since a long time, at over 37 deg C, using a Bosch AHS 55-16 (2,7kg) 450W electric cutter and a super tweaked body powered prosthetic arm with a Hosmer model 6 (back lock containing) work hook. The work contains overhead as well as low down feet height cutting.