Tskoe,

Here is a walk-through of how I made my bullhorns. First, find an old pair of drop bars, preferably alloy, and gather a few necessities:

Ruler, marker, tubing cutter, file, and clamping device. Next, secure the bars and mark the halfway point of the curve:

Then, the tubing cutter. I prefer this to a hacksaw or Dremel because it's quick and tidy. Line the cutting wheel up with your mark:

(This is a demo on scrap tube, but you get the idea)
Roll the cutter around toward the wheel, tightening the cutter as you go:

You should have a clean, straight cut:

Then, file the inside so that your end caps will fit:

And you should have something like this:

You can mount the brake levers either way, depending on how much cable you have to work with:

Re-install, re-wrap, and ride with magnified coolness