How can a generic idea like this be patented? This is bullshit!
As if any self respecting engineer would design a device with sharp corners.
Which is not only incredibly obvious, but also has a decade of prior art that could potentially invalidate it. Though I think was the USPTO is allowing here is the described mechanisms behind the concepts, not the concepts themselves.
The USPTO has a very specific goal: to maximize the number of patents which are granted, so long as they are valid by the USPTO's rules.
Those rules do not require or even allow for a working example or model of the claimed invention(s). They also define the term "non-obvious" in a remarkably non-obvious way.
Look at the great many "something obvious ON THE INTERNET" patents that are out there and in some cases being enforced.