The general purpose of these designs are described in “Electrolysis Activation of Fused Filament Fabrication 3D Printed Electrodes for Electrochemical and Spectroelectrochemical Analysis”, which is published in the journal Analytical Chemistry. DOI:10.1021/acs.analchem.9b01331 This particular part is a simple square design to fit within the 4-point probe instrument used for conductivity measurements. We have printed this part using both ProtoPasta (https://www.proto-pasta.com/products/conductive-pla) and BlackMagic (http://www.blackmagic3d.com/default.asp) PLA-composite 3D printing filaments.Details regarding the conductivity enhancement can be found in the post-printing information. Activation of the electrode (enhancement of the conductivity) of this part can be achieved through a soaking process. Enhancement over 3 orders of magnitude has been experimentally determined. For the soaking process, 10 mL of a 4M hydroxide solution can be used. The optimal time for this electrode was found to be 6-24 hours when using the BlackMagic Filament and 24-72 hours when using the ProtoPasta filament. In our studies we used sodium hydroxide, which can be purchased online. Please note that high concentrations of hydroxide are corrosive and should be handled with care! Sodium hydroxide: https://www.amazon.com/Sodium-Hydroxide-Pure-Grade-Caustic/dp/B06W57NL8S/ref=sr_1_3?keywords=sodium+hydroxide&qid=1554747032&s=gateway&sr=8-3 To prepare a 4M solution, mix 16 grams NaOH with approximately 100 mL of water. Note that this is an exothermic process and should be performed in a well ventilated area.