Complex sentence: In use, Worbla is warmed up to boiling water temperature, usually with a hot air gun, and then draped over formers or hand-moulded (wearing gloves) to shape.
Split into simpler sentences: In use, Worbla is warmed up, usually with a hot air gun, until it becomes formable at. It is then draped over formers or hand-moulded (wearing gloves) to shape.