The little clip for the inductive tach connection is indeed ferrous. I thought it was copper. but my magnet says otherwise. Must be anodized, or maybe copper plated. It looks pretty easy to replicate.
It is basically "U" shaped with squared corners.
Both arms and the center section are very close to 1/2 inch long. The two arms have rounded tips.
The middle piece has a hole drilled offset from the center, about 6/32 from one of the side legs, to allow the clip to slide onto the threaded post of the tach connection and position the legs over the two metal tabs rising out of the tach connection.
The rounded tips of the arms slide down into the slots next to the two metal tabs with round tips rising up out of the tach connection and make contact with them.
The arms are about 6/32 wide and the center section is wider at about 10/32, probably just to make a firm seat for the knurled nut and toothed washer.
There also is a small hole in the center section roughly at a mirror image location of the hole for the threaded post. Smaller than that hole but I do not know if it serves any purpose.
Material thickness looks to be 1/32.
Hope that helps.
Gene