@darrin1200 - I'll be looking forward to seeing what you come up with for those BlueDew nibs. I love the broad edge set you made!
@Empty_of_Clouds &
@Aries M - I had a Noodler's Creeper and an Ahab, but I gave them away, because I wasn't using them much. They didn't have as much line variation as I was hoping for for drawing, it took a lot of pressure to force the flex, and was comically ill-suited for pointed pen calligraphy.
I've modified a few Jinhao 450x and 750x pens to take G-nibs - once you get them situated right, they work great, but don't last long. The nibs corrode and the nipple-couplers to the ink reservoirs break, and occasionally I stab myself trying to get them apart for maintenance (once I ended up with a tiny accidental tattoo because the sharp nib had ink on it). On the other hand, they only cost about US$5-$10. They are heavy too (I prefer a lighter pen).
@Erica McPhee - those StoneGraph pens actually look a lot like Jinhaos, but 5 to 10 times the price. I assume they're made of higher quality, more durable materials, and might be worth the price for pre-fitted flex nibs though.
I also have a Conklin Duragraph with an "Omniflex" nib - wooden body, nice looking. But too stiff for real calligraphy, and not even very good for drawing. The hairlines are not very hairlike either. Disappoint.
I got a Fountain Pen Revolution pen with a flex nib - but I accidentally crushed it. It was better than the Conklin, with finer hairlines than the Noodler's pens, but not as fine as my favorite pens: the Pilot Elabo and the Desiderata.
My favorite flexible fountain pen is a Pilot Elabo (essentially identical to the Falcon) with an "extra soft, extra fine" nib. It has a feather-weight resin body, a screw-syphon fill, a 14k gold nib (which explains the price), ebonite feed, and great line variation. The hairlines aren't as fine as the G-nibs, although the nib is more flexible and softer. Highly recommend though - the whole writing/sketching experience is so great.
My next favorite is a Desiderata pen (
https://www.desideratapens.com/about), which is built around a G-nib. The proprietor hand-turns the pen bodies and ebonite feeds, so they are beautiful but also expensive. Mine has a beautiful, lightweight ebonite body and feed, with an eyedropper fill that holds a lot of ink. I really love sketching with it, and it can do pointed pen calligraphy. It "burps" occasionally, as dropper feeds do, but I use it mainly for quick sketches and kind of like the spontaneity of the little ink blurps. Then again, those blurps also leave you with inky fingers, and I never travel with it, because of the danger of leaks. And the danger of pen burp blurps might be a deal breaker for someone wanting really pristine Copperplate. But if that's you - you're using a dip pen anyway.
I really enjoy refurbishing vintage pens, so I have a few pens with flexy nibs from the 1920s-30s that I bought at flea markets and junk shops. The Pilot Elabo comes close to the flexiness and feel, but there's nothing exactly like them on the market these days.
Why yes, I guess I do buy myself a new pen every time I finish a big commission....why do you ask?