gear-like disks side-by-side with teeth cut from them that pull the plastic in while shredding it (in contrast to this lower-throughput experimental DIY shredder made with two steel pipes).

You won't have to turn the shredder on and off as you work. If you frequently shred large piles of paper, consider a model like the Swingline EX100-07 Stack and Shred ($225). It lets you stack up ...