On fountain pens you can seal the pen body with silicon grease and then instead of putting ink in a container like cartridge or converter you just put it direct

On fountain pens you can seal the pen body with silicon grease and then instead of putting ink in a container like cartridge or converter you just put it directly in the body of the pen. https://www.jetpens.com/blog/How-to-Do-an-Eyedropper-Pen-Conversion/pt/308 https://www.jetpens.com/blog/How-to-Do-an-Eyedropper-Pen-Con...