First thing I cut up a Priority Mail envelope into long thin strips.

By making slits in both ends of each length you can join them together.

Cast on loosey goosey as it won’t stretch at all

Because it is apparently a federal offense to use Priority Mail envelopes for anything other than actually mailing something I thought I better say that I’ve recycled this one.
Have you ever tried to rip one in half? I believe it’s made of Tyvek, the stuff they wrap around new houses to keep moisture and wind out under the siding. It’s really strong.
I cut long strips and connected them to make a ball of “yarn”.
The question is not ” what will you use it for or DO with it?”
The question is “was this a FUN project?”
And the answer is “YES!”