Oncee you have a vertical slice of the game, or prototype, post it up so we can play. Games live and die on their gameplay; you gotta make sure it's nailed.
Rendermap will do it. Set the sampling to 'Vertices Only', and surface type to your Vertex_Color. You probably want to bake the Illumination Only option if you're just doing light maps.
lovely work man! only one thing: the fishnets should be at 45 degrees instead of almost vertical... unless you have your own reasons for having them like that.
Looks pretty sweet. It's rare to see a concept gun that actually looks like it would work in reality. The edge tightness looks fine but the vertical foregrip looks a little murky.
The CPU could only do integer math instead of floating point. Vertices were calculated along a 2D pixel grid at low precision causing them to "snap" into position.
The one vertical brick at the edge is going to make the tiling very obvious. Also if you are bring this up to date with PBR engines. You don't want any lighting in the Albedo.
Hold shift and left click to rotate the sky around the vertical axis, other axis are locked I'm afraid. Use control instead of shift to give a rotation speed to the sky