So, you want to program a bootloaded AVR. Or possibly, you have an Arduino Lilypad and no way to program it. There are a few solutions available to you: You could buy a USB to FTDI adapter (available at Adafruit, Sparkfun, etc), you could buy a simple FTDI cable, or you could build something. I couldn't afford the "FTDI Friend," so, I decided to build an adapter to use the TX/RX Serial connection from the Arduino. It plugs in to the RX, TX, Reset, 5V, and GND pins on the Arduino and has a 6 pin female header for the FTDI connection. This can most likely be made with electronics supplies you already have.
Step 1: Materials
Not much is needed at all for this. The only materials you need are:
-6 Pin Female Header
-6 Male Header Pins, broken into sections of 4 and 2
And the only tools you need are:
-Hemostats help a lot with holding the wire in place
-Fine Tip Permanent Marker