The original image seems to be somewhat fine for perspective, as it is most a flat image from the side. Adjusting for perspective, however, is often something I try to do by hand and guess work. Sometimes the item in question has no real world sense of scale (very true with many video game items). This makes the transition into the real world tricky. Items from the Warcraft world, for example, have comical scales for real life but fit well in the world they inhabit. The trick is determining whether to keep the ideas of create a "real" version. In the above, I scaled the imaged before I traced it; however, the image I posted in response was a screen cap so it lacked the correct scale. The scale I have in inkscape is locked in and based on the know size of firearms of that style (Lewis gun is 50ish inches long, the scale I used put the item in around 51inches based on hand size scaling), the size of human hands, and the general aesthetics I want. This is the "Art" part of the thing, though I admit I am not as good at that part. All I did was glorified tracing and some math.
