Ballpoint Pens vs Fountain Pens

> Time Span for Ink Cartridges (Winner: Ballpoint Pen)

I believe if you use an eyedropper fountain pen, one 20ml ink bottle will last you more than the 3kms that the Ballpoint Pen Refill promises.

After all, most cartridge fountain pens can be easily converted into eyedropper mode.

I am a microfluidics engineer, and just love holding a marvel of fluid mechanics engineering in my hand as I think/write.