TWSBI Eco Fountain Pen - Serpentine with Bronze Trim and Nib
A serpentine green with quiet visual depth
The TWSBI Eco Serpentine is a limited edition piston filler with a mixed resin finish inspired by the tones of serpentine stone. The blend of greens and browns varies slightly between pens, so no two are exactly identical. Bronze trim adds a warmer contrast to a design that otherwise stays very functional and familiar within the Eco range.
What sets it apart
- High capacity piston filling system, for long writing sessions
- Reliable steel nib, available in multiple line widths
- Mixed green and brown resin with subtle variation between pens
- Transparent barrel allows you to monitor ink level easily
- Lightweight and balanced design for extended writing comfort
Feel in the hand
The Serpentine feels familiar in the hand, but visually softer than brighter Eco finishes. The green tones reduce the stark demonstrator look, which makes it easier to settle into longer writing sessions without being visually distracting.
Who it’s for
- Writers who prefer natural, earthy colour palettes
- Users who want reliability and capacity in a good looking pen
- People who enjoy demonstrators with a more refined finish
- Anyone who writes for extended periods
- Urban sketchers who will enjoy the more 'earthy' appeal
Not for
- Users who prefer bold or highly saturated colours
- Those who want cartridge or converter convenience
- Writers specifically looking for metal or gold nib luxury feel
- Sketchers who prioritise waterproof inks over pen aesthetics
Practical tips
The resin pattern varies slightly from pen to pen, so the appearance is never completely identical.
FAQs
Is the Serpentine fully transparent?
Yes, it has a clear demonstrator barrel, with only the lid and end knob opaque
Does it use cartridges or converters?
No, it uses a built-in piston filling system that holds about double a cartridge
Is it suitable for beginners?
Yes, it is one of the most beginner friendly piston fillers available
Can it handle document and shimmer inks?
Yes, with regular cleaning recommended
What nib does it use?
TWSBI stainless steel nib, with a bronze coloured plating to match the trim
What’s included
- TWSBI Eco Serpentine Fountain Pen
- WrenchÂ
- Silicon grease
- Simple gift box
- Instruction booklet
- Free nib tuning by LarryPOST
Ink pairing suggestions
- Forest green inks match the body without overwhelming it
- Olive tones soften the overall look further
- Brown inks add warmth and contrast inside the demonstrator body
- Teal inks create a sharper visual contrast in the barrel
Build your practice
- Replacement Bronze Eco nibs, for exploring line widthÂ
- De Atramentis Document ink for permanence
Specifications
- Brand: TWSBI
- Brand series: Eco (plated)
- Launch:Â June 2025, second in Feb 2026
- Origin: Taiwan
- Nib:Â Stainless steel
- Nib sizes:Â EF, F, M, B, 1.1mm stub
- Filling system:Â Piston filler (1.8mL)
- Body:Â Transparent polycarbonate
- Trim:Â Bronze coated steel
- Cap:Â Twist
- Grip: approx. 10mm
- Diametre: approx. 13mm
- Length:Â approx. 139mm (capped)
- Weight: approx. 21g (capped)
- Comparable size:Â Lamy Safari, Pilot Metropolitan
Still an Eco, just with more visual depth than usual.
