I would bet there is zero vacuum bag involvement.
I'd prefer a vacuum bagged heat cure to direct bond to the metal.
But even gluing a curred sheet I'd want a vacuum to prevent bubbles.
I did some repairs without vacuum (pre cured patches) and with vacuum (pre-cured, pre-preg, and wet layup) and the vacuum looked better in all cases (as well as stronger, but that's not an issue here).
I don't even like fiberglass w/o vacuum now.
As for a hand wrapped CF mod, wrapping a metal tube and other bits for conductivity/strength (composites are often brittle and don't like fasteners) sounds quite doable.
I wish I had an oven to cure one. The vacuum part is easy enough.
And like so many things, cost of material for a one off is high because of minimum quantities. But amortizesd over a few dozen it's not bad.
I looked for pre-preg CF sheets a year or so back. Just wanted a few to play with. But I'd have to buy dozens.
Same with cloth and resin. Couldn't get just a few yards and the resin only came in quantities 20x what I wanted.