Has anyone ever had experience with 'precious plastic' or similar?

Kind of. I'll have to check out their shredder designs. I bought a filistruder for a local makerspace awhile back, because I wanted to be able to reuse my bad 3d prints and supports etc, but wanted it to be available to a wider community since I wouldn't use it enough to justify the cost. Unfortunately, at the time, solutions for shredding/granulating solid prints were few and far between (and expensive to make or buy). And if you can't get the plastic small enough, the extruder on its own isn't terribly useful. I'd very much like to find a decent solution so I can get this going again.