Looking in the old posts from a couple years ago, I see that the saw blades were tried and discarded.
Looking closer at the design i see that the gaps were quite large in the anvil the blades cut against.
Also in commercial machines that use high speed cutting, a flywheel is used to even out the speeds.
I think this concept should be re-visited
someone revisited 
video of the output and you prob should slow it down a bit the blades. standard high speed shredders are running at 500 rpm.
Works… rather too well…
Still lots to be done…
https://www.youtube.com/channel/UCSqXUxHfFUYEp7Oo7YMjrsw?view_as=subscriber
… until somebody drops a stone in it.
if one had a proper enclosure for the spinning blades, much like the high speed shredders do…
@3dseed ‘Guenter’ ? Isn’t that the guy who’s eating little kids – with saw-blades as teeth ?
@ppolice … is that you Gunter…??
Yeah, it should be a standard on Youtube that at the end of each video the author places both hands into the camera shot.
Of course, a safety tie and engaging safety squints should cover it.
On the other hand, I think there is a trade space in blade diameter and speed between the typical paper shredder and the PP shredder, especially if one is willing to pre-process some of the plastic.
‘saw blades of death approach, the spacers between the blades probably want to be almost full diameter’ – yeah, indeed – it gives me just nightmares thinking about doing & completing this machine even with the best tools around.
Folks, sometimes it’s best to ignore this sort of wishywashy stuff on Youtube – if they don’t popup with follow up videos or better versions – save your time & money 
Eventually you could knock out a a few portions of the discs but then the risk of fractures and a nice face decoration is getting just higher …
I’ve been thinking about the saw blades of death approach. Since it will be taking very small bites, the spacers between the blades probably want to be almost full diameter to support the blade. I like the threaded compression mount you show.
