Custom M4 Model

thingiverse

I envision my custom M4 like this, and I think it would look fantastic. It's possible that this design could be printed in 3D, but I was considering machining it out of aluminum using a CNC mill instead - which would use significantly less plastic than printing. My problem is that I'm having difficulty converting the STL files into a solid object. This custom M4 would make an awesome prop.