Is it possible to make
your own weed eater trimmer string?
The video is in Russian, but
you get the idea from watching it that common plastic bottles can be
converted into a spool of plastic ribbon with what seems to be an easy
to make metal jig.
I'm sure the stuff you buy in
the store would last longer, but the feeling of making your own might
be worth trying it to see how well it works?
Wether the strips that you can make from a bottle are useful in a weedeater depends on the kind of material the bottle is made from.
Weedeater strings are usually made from nylon. Water bottles are generally made from Polyethylene Terephthalate (PET). Soft drink bottles probably have a layer of different plastic on the inside. The ultimate strength of PET if generally significantly less than that of nylon. Also, strips cut from a bottle have a different cross-section from (generally round) weedeater strings.
Don't bother with polyethylene (PE) bottles. Its strength is less than half that of nylon. My guess would be that those strings break easily.