Magnum Exh manifold machining.

I have an idea what might work. Thinking about the flattening jigs woodworkers use for getting a table top or other surface flat using a hand router. Basically they build a movable gantry/carriage in which the router sits, then they simply place it over the work piece and pass the router over a billion times and end up with something that matches the plane of the carriage.

I could mount a 4" grinder onto a carriage like that and as long as everything is locked into place, just keep sliding the grinder back and fourth until the material is removed. Like a hillbilly surface grinder.

-=C