I'd already made the panel and offered it up to the battens. Now for assembly:

These are the battens, glued to the panel with Sikaflex (awesome black rubbery glue used in marine applications). The black stuff is a bit of anti-drumming rubber (which didn't have much effect, to be honest).


Up goes the insulation. I've used mineral wool for most of it, and sheets of thin foam where space is limited. This is held in place with spray carpet adhesive. Remember where every book says use gloves and a mask and goggles? I didn't. You should. Cough, cough, wheeze!


Next is a moisture barrier, to keep people's wet breath off the metal panels (if the insulation got damp it would never dry and the door would rust from the inside out). This barrier is just a plastic rubble sack and it's held up with gaffer tape. The panel will screw through the barrier into the battens, which I think ought to be OK.


Finally the panel goes up: it's held on with 1" #8 woodscrews into the battens; the black spots are concealer covers for the screw heads. The two black recessed panels are to be magazine/map racks, once I get some elastic mesh in place.


Of course the next day was scorching hot and the carpet started sagging from the panel - I might have to reglue with something better than carpet glue!