The Kaweco Sport is a very popular pocket pen with one drawback, it doesn't hold much ink and there are not very many options for converters that work with it. Here is one way to resolve this short coming, it's referred to as a bulb filler. It is said the idea came from 'dcpritch' on fountain pen network, and a the gent from Fountain pen day make an instructional video as well. Video by Fountain Pen Day

     It is a simple cut and paste project. All you need is 3 things; an emtpy Kaweco cartridge, a #18 latex or #20 silicone sac, and shellac. The cartridge is cut with 5mm of the body remaining to glue the sac to. I found a #20 silicone to fit and preferred the clear ink viewing property of this option. The sac is cut to a length of 45-48mm, then shellac was applied to the outer surface of the 5mm portion of cartridge. Put the sac onto to cartridge. While drying connect the assembly to the Kaweco section and align the sac to extend straight outward from the section. When removing from section be careful not to pull off the sac as the shellac will take roughly 45-60 minutes to dry.


    This new bulb filler will nearly double your ink capacity for this pen over the Kaweco bulb converter plus you won't need to refill cartridges to use the ink you prefer.