This LCD  module can be used with 3d printer RAMPS shield. It works as a monitor and manual controller for your 3d printer. Using this module you can print your design without requiring a computer be connected to your printer. 

The module contains and 128 x 64  backlit LCD display, buzzer, SD card reader, and control inputs. The module also includes cables and adapter board for solder-less connection to a RAMPS shield. Power is taken directly from the RAMPS shield so no additional cabling is required.

Manual axial movements for the printer head and calibration  can be done using the rotary encoder. You can upload the g-code of your design directly using SD card.

Package include

LCD20x4 module with SD card and encoder
L-shaped adapter plate
FC cable

Instructables detailed tutorial Wiring 3D Printer RAMPS 1.4 including LCD smart controller