The weirdest thing I’ve seen is a slap bass standup player in a rockabilly band playing clear strings. The bass sounded good for slap and I asked him what kind of strings he was using. He told me “weed wacker.” Turns out he had left his bass in a friend’s warehouse and rats had eaten his strings. When he found out how much new strings cost he started looking for alternatives. He had read on the net about players using nylon strings and went to his local Home Depot and found the replacement weed wacker line and asked if the line came in gages. He bought 4 gages that most closely matched normal string gages and the rest, as they say, is history. [or histerical…] He told me “I got four rolls of strings for less than the cost of one string, they last, what I have will probably last for the rest of my life and the rats won’t eat ‘em!”

Can you tie a knot?

I dunno, I've done a bit of weedwacking in my day and seems the string is too tough to be tied easily.

Maybe if one applies heat they could melt the ends of the string into fat globs.

Also worth noting that this will not work on an electric bass...