I called my customer last night and asked him how he made his jig to hold the plug.

He says someone now makes one that clamps on to the bumper. He did give me an on the cheap way to grab the plug to get the shell off.

He says just use an old spark plug socket and grab it in a vise. Cut through the shell and then grab the plug and turn it one flat and cut some more.

There is no reason not to cut the plug apart.