We were somewhere around Barstow, on the edge of the desert, when the
drugs began to take hold. I remember Lobster
saying something like:

It would need to be something that's easily demountable by hand, would
not leave a markedly protruding fitting on the wall when demounted, and
would not involve me in lots of metalwork (other than a drill, hacksaw
and file I just don't have the kit!)

Employ a passing urchin for a couple of hours.