The Kaweco Sport fountain pen is brilliantly designed and reasonably priced. When it’s capped, it is compact enough to fit in any purse or pocket, and when it’s posted, it is the perfect size for writing. However, one downfall of the pen is that it can only be used with short standard cartridges, wasting the space of about 1/3 of the barrel. Also, it cannot be used with a converter so writers cannot use their favorite bottled inks with it. (UPDATE: The Monteverde Mini Converter will fit inside the Kaweco Sport fountain pen.) To resolve these issues I converted the Kaweco Sport fountain pen into an eyedropper fill system, where the barrel is used as the ink reservoir. To prevent ink leakage I used 100% silicone grease (petroleum free) to seal the threads. Hopefully, this explanation will help other writers maximize their Kaweco’s potential.