Always Render/Draw FPS Weapon

I am trying to make it always draw/render the weapon even when its "poking threw objects". How would I achieve this using only one camera?

Take a look on this shader shader, maybe, it can help you:

http://www.unifycommunity.com/wiki/index.php?title=DepthMask

in the documentation says that you need to add a line in all your shaders:

Tags {"Queue" = "Geometry+20" }

And apply the DethMask shader to your weapon.