This design is loosely based on the Solder-Mill with a roller and hole to feed solder through.
Print 2 of the nibs (solid) and 1 roller and 1 base. I would make the roller around 20% infill and the base solid.
Then glue the nibs into the end of the roller, if you print in ABS (preferred) then you can just use a few drops of acetone, the rounded end of the nibs point outward.
Simply feed solder through hole in front, slide roller into roll of solder and slide into place.