Use of conductive material for the resistor parts and PLA material is recommended for the rest.
The uploaded files contain STLs for a printer with a dual or single extruder. Using a single extruder, each printed layer should be glued.
The supports for the dual extruder files have been added and should be printed with PLA, the bridge speed (the conductive material) should be at 8 mm/s to 15 mm/s and the height layer at 0.1mm
Also, a calibrator has been added. For assembly instructions check the relative included STLs.
Components list, arduino code and more on:
Low-cost PLA with good quality: