Pull plunger out of 2 syringes and put aside.  Cut the top and bottom off the syringes with a razor blade (see photo).  Epoxy a valve into the ejection end of each one and let dry fully.

Solder the PI into the Sparkfun breakout board, solder on a 1K resistor (the board says to use a 220Ohm resistor but we found 1K doesn't impair the function of the PI and consumes less power), and solder on the 3 pin JST connector. Be careful with the orientation of the connector, it's important!  Plug the wire into this 3 pin jack.

Connect:

1.  The ground pin on each photointerrupter to the GND on the Arduino
2. The power pin on each to the 3.3V on the Arduino
3. The signal pin on one photointerrupter to pin 7 and the other to pin 8

You can push the wires into the headers on the SD shield or solder them into place for a more permanent connection.

TODO: Write up testing methods