These are a couple pics of the parts for the reactor that will collect electrons and make current. Four main pieces, casing, salt bridge tube , lid and electrode holders. Here are 3d pics of the designs before printing, I will post the files for use by anyone. I may add my name to the pieces to mark them for future use.

Here is the cell with a divider to separate the anode and cathode aqueas solution

This is the salt bridge, the salt bridge is a salt enriched gelatin that is a semipermeable barrier  that allows electrons to flow , but not allow the aquaes solutions on each half cell to mix.

inside you see the U shaped tube is printed hollow to fill with salt gel

This is the cell topper , two holes allow for the salt bridge to be installed. The two further holes are for the electrode holder, since the electrodes are wire I would have something to wrap them around. The topper has a inner ledge that drops down into the cell and the divider is offset, so when removing the cell top, you cannot put the cell electrodes back in backwards causing polarity to be wrong.

The first version of the electrode holder was solid with infill. I found that making the hold hollow like a tube significantly reduced the print time and amount of filament used.

All parts shown together , cell casing, divider, U tube , and electrode holders

Final Proposed assembly of the urine fuel cell.