Blogger "Istimat" has posted a blog documenting the 3D designing and printing process of a Half-Life 2/Turret Sentry Gun that is still a work in progress. Inspired by a paper craft "pepakura" model, the design must ensure that the gun's turret can rotate side to side about 90 degrees, with the ability to move up and down and point at the face. Istimat is well on his way to pulling this off, and it is rumored that it may even shoot mini marshmallows, or hollow 3D printed plastic marshmallow bullets, when completed. Read more at 3DPrint.com: http://3dprint.com/119035/3d-printed-half-life-2-gun/