Twisted-pair wire is quite handy for many projects, particularly for power wires, connections to switches or LEDs, etc.  But, it's not something I've ever been able to bring myself to buy when I'm ordering parts because a big spool of it can be relatively expensive.  So, I decided to find a quick and easy way to make my own.  Twisting wire by hand is one way, and not too bad if you're just making a short section, but it's not exactly quick for doing larger pieces at once, and you don't get a very uniform, stable twist.  Power tools make everything easier.

What you need:
1) Some suitable wire - ribbon cable you can peel apart is great, or a roll of regular wire is fine also
2) A reversible handheld drill

We start out with some ribbon cable.  I have always managed to come across quite a lot of spare ribbon cable that nobody wanted at school or work - ribbon cable is a great thing to have around because you can tear off as many conductors as you want.  This particular ribbon cable is made of some pretty thick wire so it's not very flexible, and thus it's not very desirable for most places you'd want to use ribbon cable - but when you peel it down to one or two wires, it's plenty flexible.  

So just start off by peeling the ribbon cable apart into individual wires. 

Grab two wires, and fold the end back over itself an inch or two and hold it with some tape.

Secure this end of the wires to something.  I duct-taped it to my desk, but if you have a nail or hook or something you can just loop the wire over, that is probably easier.

 Put the other end of the wires into your cordless drill chuck and clamp them down.

Now pull back on the drill to pull the wires somewhat taut, and use the drill to twist them.  Keep a moderate amount of tension on the wire so it twists evenly and doesn't knot itself.  Twist it a little more than you want it to be twisted, and then switch the drill into reverse and spin it back a bit to let the wire relax.  This will prevent the wire from bundling itself into a ball as soon as you let off the tension.  This whole process takes just seconds.

And there you have it, a nice little roll of twisted pair wire.  In very little time you can turn a big piece of ribbon cable into a whole bunch of twisted pair, and if you use rainbow colored ribbon cable you get the added bonus of all different colors.