These are my lazy equivalent, I don't use many now either, and they badly need a clean...:
Take a piece of twin-wall polycarbonate (this came from Two Wests & Elliott but can probably be obtained cheaper elsewhere).
Take two pieces of stiff garden wire (from Wilkinsons in this case)
Thread wire through between walls of polycarbonate and bend at right-angles at each end.
Wires can be further adjusted to lodge between rockwork or pushed into soil etc and the whole thing folds flat for storage.
(No - the Aciphylla in the picture doesn't need a cover - this was put there for the photograph.)