My plastic guy wasn't around so I did a few samples out of cardboard.
This would be super easy. They could be cut with just a water jet machine like the roost caps. Just a round disc with 2 holes in it for screws. Probably make it out of 3mm thick aluminum. It would be less money like the Roost caps. Probably around $85-$95 a set.
These will be a little more difficult. The R&D would be the most time consuming. But if I could get a solid template I could still have them done with the water jet machine. It would just take a little longer with all the curves. The downside is, you would have to drill your own screw holes. I checked a set of Throttles (pictured) I have in stock and the screw holes location in comparison to the lug holes was different on each wheel. And since this cap would be built around the 6x135 lug pattern, you would need to drill your screw holes accordingly. Price would probably be closer to $150 for the extra time in the machine.
The other thing to take into consideration is the shape of the wheel. The wheel is kind of curved down as you get closer to the hub and the cap would be flat. So at the inner most part of the lug nut the gap would be slightly bigger. Running lugs like yours you won't see it but I'm sure water will get in there when it rains or when washing your truck.
