I don't have all the details in front of me right now, but I can give you a brief explanation:
This is made from a piece of 1/4" thick 2x2 angle iron. There is a cutout that straddles the stringer on the pallet. The pieces on each side slip under the board you want to remove.
The round circle is a pipe that gets welded on to the angle iron and used as a lever.
I haven't made one personally (haven't got around to it yet) but it should let you bust up an entire pallet in about 10 minutes.