Applying Material Extrusion Printing Process can fabricate simple Functional Electronics using the composite material. The design of the object, the layout of the electronic components and the circuit information are reflected in the CAD design. The exterior of Functional Electronics is printed with external cases for visual design and user interface modules and electronic circuits and electronic components slots are printed internally. Therefore, an integrated design should be preceded including the placement of electronic components and circuit inside the three-dimensional structure. Also, the printing material should be specified whether used as plastic or conductive material depending on the function and roles to implement. And it is required to distinguish printing area per each material. Ag paste, GO mixed PLA and eutectic alloy are used for the conductive materials. Low-melting point alloy metals that can be printed at temperatures similar to plastic materials, so electronic circuit can be immediately printed without post-processing. Also, it does not give thermal damage to the plastic structure, and a post-processing is not required. By using 3D printing process, We fabricated a 3D structure which is embedded user interface and LED light circuit. Circuit design and fabrication technologies that are not constrained to the boundary of the dimension are expected to increase the use of 3D printing technology in the electronics industry.