This mech paper model is Shadow Cat, a heavily-armed and maneuverable medium OmniMech developed by Clan Nova Cat to replace the Ice Ferret in the early 31st century during preparations for Operation Revival, from the video game MechWarrior 3, the papercraft is created by Cantaris, Madcatmaniac and Sturm. The size of finished model is about 200 (H) x 179 (W) x 154 (D) mm.
Use of the Shadow Cat has spread to other Clans since its introduction, most notably, the Annihilated Clan Smoke Jaguar, Clan Cloud Cobra, Clan Fire Mandrill, Clan Steel Viper, Clan Diamond Shark and Clan Wolf. First encountered by Inner Sphere forces at the Battle of Luthien, the Shadow Cat was subsequently used by the Clans during the Battle of Tukayyidagainst ComStar. It is one of the few invasion-era clan mechs to lack a separate Inner Sphere designation; all Inner-Sphere pilots who encountered it before the battle of Tukayyid died, and Com-Star was informed of its designation before that battle, resulting in both sides using the same name.
The Shadow Cat was such a successful design that it has seen continued production by Clan Nova Cat well into the Dark Age period. [Source: sarna]
You can download the papercraft model here: MechWarrior 3 - Shadow Cat Free OmniMech Paper Model Download