This mech paper model is Champion, a BattleMech from the game Classic BattleTech, the papercraft is created by Yogsolthan. The size of finished model is about 198 (H) x 179 (W) x 105 (D) mm. There is also a MechWarrior 3 - Champion Paper Model on the site.
You can download the papercraft model here: Classic BattleTech - Champion Free Mech Paper Model Download