Thanks Kirky,
It's planted on a nylon slab (cut from a heavy duty nylon chopping board) like Michael Hagedorn does:
https://crataegus.com/2012/03/31/mounta ... lon-board/
I made 'feet' for the board with the plugs I drilled out of the board using a hole-saw. You can easily stick them back onto the board with a blow-torch.
Pearcy,
It took ages. No idea how long, but probably a day's worth. Had to make a trip back to my 'moss spot' to get more. Shame most of it is the one species, but hey, beggars can't be choosers. Who would have thought good moss would be hard to find along the coast of the world's second driest continent....