For the Ramps, yup, an extra driver (you will need to set the voltage), an extruder kit (e3d or MK8 (back in stock soon)), a print fan, extruder mount. Depending on the size of your machine you will probably need to extend all the wires.
The board will need to get flashed with thermistor enabling firmware, I have the MK8 firmware ready to go, but the e3d is just as easy.
A heated bed is highly suggested, and that requires a power supply of at least 20A.
A more fun way to do it is use your mpcnc to cut the frame and make a mp3DP, a standalone printer really is better/faster if you think you will do some printing. The cnc tends to get really dirty, not a good combo with a tiny nozzle.