Baker's twine is apparently the rage right now in papercrafting. I knew I could easily make some with a simple tool. I got this hair twisting tool for my daughter several years ago, so if you don't already have one you'd have to search online.
A spool of cotton crochet thread I've had around for ages and some embroidery floss is all it takes (or you could use white floss).
I separated the 6 strand floss into 3 strands but you could try it with different amounts. I cut the floss and thread about the same length and tied a little knot at one end of each to help keep it from being pulled out of the tool's hooks while I'm holding it. Put the floss under one hook and the thread under the other. The thread twists in 2 steps. The first step puts a twist in the individual strand on the hooks.
The second step then twists the 2 twisted strands together. You can make this as loose or tight as you like. There will be a couple inches of untwisted strands close to the hooks. Keep that in mind when determining how much twine you need for your project.
Here are 2 finished pieces of "baker's twine" - the red was twisted a little tighter than the blue one.