[WCSTombs]

Totally agree about the company. Specifically, the Uni-Ball Signo UM-151 black gel pen (0.38mm) is my all-time favorite non-fountain pen at this point. (The most popular competitor is probably Pilot's Hi-Tec-C/G-Tec-C, but the Uni-Ball is just superior IMO.)

About the article: this is really cool! One thing that I can't help thinking about though (not to be a negative Nancy) is the opacity of the barrel is probably going to make it much more difficult to tell when the ink is running out. To be clear, though, that's a secondary concern to the plastic reduction, which is amazing.

The ultimate combo with this would be affordable and durable third-party (or first-party) compatible pen bodies themselves. There are third-party metal pen bodies compatible with many of the popular pen refills that are sold, but last I checked they were so expensive that the economics didn't make any sense unless you really burn through the refills.