Certainly it's possible : I've made 2 some time ago...
It won't win a beauty or performance contest, but if you can get them for free, it's worth a go.
I wanted to try making a flemish string. (like here
http://poorfolkbows.com/flemish2.htm)
I took 2 halves of such a bail twine, and made the blue one in the picture.
It's a bit overbuilt, and rather thick for a string, but it works...
Then I got a orange nylon cord and took about 1/3 of a bail twine, and about as much of the nylon cord, and made the 2 color one...
it was a good learning exercise... and I do not even hope to make beautiful bows comparable to the ones posted over here for the foreseeable future... what's in the TBB again? the first 50 bows are learning experiences?
and it definitely works for "long cord" and string for tillering, in vain of something better...