Too many pens and their refills are disposable by design. Similar to printer ink cartridges, pen companies want you to buy into their format so that they can keep selling you replacement pens or refills over and over again.  It's good for their business but it's bad for the planet and stifles creativity.

As a product designer and craftsman who loves using  a variety of pens to create illustrations and designs I had this very problem! Pens would sit in my drawer for years, either patiently waiting for that very specific refill or I was just loathed to dispose of an otherwise fully functional pen that had run out of ink.

Having designed and handmade calligraphy and fountain pens for creative folks across the world fulltime for over 6years I decided it was time to apply my knowledge to the pen I used most of all and one of the biggest culprits when it came its disposable nature, the fineliner.