Looking at the Raspberry Pi Cobbler in Adafuit's wonderful collection of RPi accessories, I decided that it would be a much better method of connecting the the RPi GPIO to a breadboard than an old IDE cable with wires stuck in the end. I didn't think I could justify paying $8 plus shipping to the UK for a bit of PCB with some headers. So I decided to try and make my own with some strip-board, headers, and an IDE cable.
Step 1: Preparing the Strip-Board
Step 2: Soldering the Headers
Step 3: Adding the IDE Cable
I didn't put a socket on my Cobbler because I didn't have one and I don't think I need one anyway. I've got more IDE cables I can use for other things. Instead I cut the connector off the end of the IDE cable and stripped the ends of all the wires.
First I had to cut my IDE cable down, because it was a 40 pin cable and the Pi only has 26 pins. I marked where the connector needed cutting then cut it with some clippers through the pins next to last ones I need to make sure I didn't damage the ones I needed. Then I just pulled the extra wires off. After that I needed to wrap the connector in electrical tape because the plastic holding it together was at either end, so it wasn't staying together now I had cut one end off.
Then I stripped the wires by pulling them apart about 2cm from the end and using wire strippers to strip about 1cm of insulation off (this takes a while to get right, and the first few wires will probably be a bit messy, this doesn't matter much though). Once they were all stripped I bent every other wire to one side and rest to the other side.
Finally I soldered all the wires to the solder joints holding the pins on the strip-board. I placed the Cobbler on another piece of strip-board again to hold the pins straight. I did one side of the Cobbler first then the other using tweezers to pull the wire down onto the joint then melting the solder and holding the wire in it for a few seconds to let it heat up, then removed the soldering iron and kept holding the wire with the tweezers while the solder solidified. Again this takes a little while to get the technique right and the first few may be a bit messy.
Step 4: Final Tests
Check the fit in the breadboard again and adjust the pins if necessary. Now test it with an LED, resistor and python to make sure all the GPIO pins are working.