"Prison" Saw
https://www.amazon.com/gp/product/B08XMYQKPJ
I have to relocate drain & hot-cold plastic pipes for the bathroom remodeling. The area in the wall where I needed to intersect with the existing piping was too tight for any other type of saw, so I ordered a wire saw. The tooth was a little too coarse but it did the job. Cheap.
Seems like they would work well on PVC and ABS though... probably better than they do with logs. It's a fair bit of work to cut logs with those.
>wire saw
I remember seeing those on tv commercials for Rambo knives in the 80s. The handle of the knife was hollow and there were all sorts of survival stuff inside of it and they usually had one of these saws. The commercial showed people cutting down trees with the saw.
Found the commercial! https://www.youtube.com/watch?v=-gj9CMvwfv4
>knife
$10 !!