There are 6 of these to make after you have fluted and drilled L angles for the sides. This is a wide L angle which needs one side cut to fit the curve of the fluted pieces. I drilled them on the edge of a 3/4" board and deburred. Need to try to avoid the flutes while drilling so the pitch count is lightly different in all but doesn't exceed 40MM. I'll rivet the angles together but not to the sides until I finalize the firewall.