This is a paper model, Vash's gun is from Trigun manga series.Trigun (トライガン, Toraigan) is a Japanese manga series written and illustrated by Yasuhiro Nightow, published from 1996 to 2008 and spanning 17 (3+14) collected volumes.
The manga was serialized in Tokuma Shoten's Shōnen Captain from the series debut in 1996 until the magazine's demise in 1997. The series continued in Shōnen Gahosha's Young King Ours magazine, under the title Trigun Maximum (トライガンマキシマム, Toraigan Makishimamu), where it remained until finishing in 2008.
Trigun was adapted into an animated television series in 1998. The Madhouse Studios production aired on TV Tokyo from April 1, 1998 to September 30, 1998, totaling 26 episodes. An animated feature film was released in April 2010.