Recently, I've messed my Pilot Metropolitan's nib.
I love this pen, which is black and from animal collection.
I'm using J. Herbin Perle Noire ink with this pen, however, while shaking the pen, it dropped ink sometimes, and I wanted to fix that by manually adjusting the nib. However, this newbie attempt resulted me having a bended nib, which leaked even more. This was a bad idea. I couldn't fix this behavior.
I didn't want to throw the pen away, so I tried to find replacement nibs. I couldn't find a spare nib for Metropolitan, and I didn't want to salvage other pens just for that, so I checked other sources.
While checking Aliexpress, I saw Wing Sung 659 and 698's nib is compatible with Pilot nibs, so I gave it a shot. It's $3 on Aliexpress (I bought with $2 feed which should be compatible with pilot also just in case). The feed looked almost identical, but didn't fit into pen (slightly larger), but the nib fit into Pilot's feed just nicely, and here it is.
The replacement nib's tines are a little bit longer, but writes beautifully, and F is almost identical with Pilot's M. This "frankenpenish" attempt resurrected my pen.
In the photo: Left: Pilot MR-3 (nib is identical with metro) with Pilot nib, Right: Pilot Metropolitan with Wing Sung nib.