Clamping to a mill table

[Occasional machinist]

A couple of people have suggested something like that. Two reasons why not - firstly, I wanted something with a hex the same size as my hold down clamp nuts - so I could use the same spanner (11/16"), which is larger than normal for this size pad (across the corners of the hex is the same diameter as the pad).
Second reason was that I hadn't done a form tool like that before, so this was more interesting!