This is felt tipped or other porous-tipped pens and markers.
Here's a great set of six Gundam markers for adding color to Bandai's BB Sangokuden series of Gundam kits! The markers can also be used on other Gundam kits, too. This set contains a water-based black marker for panel lining and five alcohol-based markers: GM82 Sangokuden Gold, GM83 Sangokuden Silver, GM84 Sangokuden Metallic Blue, GM85 Sangokuden Metallic Green, and GM86 Sangokuden Metallic Red.