The Copic Drawing Pen FO2 (0.2mm) is an interesting little tool. It is filled with waterproof india ink, though when tested I would say the ink is more water-resistant than waterproof, and is largely marketed as a tool for comic drawing or illustration. The pen is not refillable nor is there an ink window to be able to see how much ink you have left. But its basically a $5 fountain pen filled with almost “bulletproof” ink, so its a fairly decent value all things considered.
On my standard testing paper, Miquelrius medium flexible 300 grid paper book purchased from Barnes & Noble, the pen was not scratchy and performed pretty well. The steel nib did not have a ton of give but enough to vary line widths a little.
Overall, this wouldn’t necessarily be a pen that popped to mind if someone was asking me for recommendations for an inexpensive disposable fountain pen though I did find the line width to be much finer than Pilot Varsity and the water-resistant ink is a positive attribute for field work and envelopes.
(available from Jet Pens for $4.60. Also available in 0.1mm available in black and sepia)