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 cap designed to fit into "electrochemical cell" and hold a "standard electrode", a reference electrode, and a counter electrode. We recommend printing this design with ABS filament.