I built a homemade stir plate using cherry and some old computer parts. It was an excellent and fulfilling process. Here are the pictures:
This is a 7"x7" stir plate and fits a 2L starter perfectly. I used an old hard drive magnet and an old computer fan. It can regulated via the potentiometer. Just used old wires and soldering them to each other, the switch, and the potentiometer. The potentiometer is a 25 ohm resistor and I use a 9V/850 ma power supply. This thing cranks! So if you are interested in making your own I would use a 6V power supply instead, or dumb down the milli-amperage a bit. It was a wonderful experience and thinking about making one in black walnut next.
As for starters, I was wondering what peoples thoughts were on the 2L flask. I have heard ups and downs, especially about the durability of one. I have a 1L starter but been wanting to get a 2L starter as I am starting to move to higher gravity brews.