5K Cat Sheild Rattle

[Steve Sherman]

On cold starts, there is an awful racket coming from the outer sheet
metal sheild that goes around the catalytic converter.  It does appear
to be the sheild moving (not the insides) as slight pressure on it will
quiet things.  Once things get hot, the rattle goes away.

I am looking for ideas on how to secure this outer sheet metal to the
main case to eliminate this rattle.  Welding is not a good choice (IMO)
due to all these parts being stainless, and other than a MIG unit, the
weld would be plain steel, and introduce rust points.  I've thought
about just using some muffler patch paste at the edges; just enough to
take up the slack movement, but I would not expect that to last long.
Possibly dimpling the sheet metal up to the underlying metal?

Anyone else out there have a solution?

TIA