You could use an Arduino board as a source for your wave form. I say this because its a lot easier to manipulate and can be reused again and it's always fun to learn new stuff, assuming you're not familiar with arduino. Also you can easily change the frequency in case you move on to another project, you would just have to re code the Arduino.
You can use a NE555 timer for a classic LED blinking circuit. Digikey has a copy of the datasheet online, Search for the timer and the datasheet is linked on the product description page. The 555 timer is readily available at Radio Shack as well. Wire it as an astable multivibrator and connect the LED to pin 3 through a 330 ohm or so resistor to protect the LED, (if running the timer at around 5 volts). The circuit will also require resistors and capacitor for the RC timing network. The datasheet will have a schematic for astable mode and formulas to help select RC values for 2 Hz output. Pay attention to the formulas for time the output is high and time the output is low. Using the right resistor values for the 2 timing resistors (one significantly higher resistance than the other) can get the output closer to a square wave which should be preferable for the visual blink of the LED.