Marina Tabassum has built emergency homes for the delta-dwellers of the Ganges using grass and bamboo. Her Serpentine pavilion – part tropical glasshouse, part 70s office block – is a chic, meditative place for an overpriced coffeePast pavilions have taken the form of inflatable balloons, teetering plastic pyramids and cork-lined lairs dug into the ground. We have seen a fibreglass cocoon perched on boulders, a wildflower garden enclosed by tar-daubed walls, and an assortment of undulating canopies, clad in polished steel and jagged slate. Now, to celebrate 25 years of building experimental structures on its front lawn, London’s Serpentine gallery has unveiled its first pavilion that moves.“Every time you think of an idea for the project,” says Marina Tabassum, the Bangladeshi architect behind this year’s kinetic enclosure, “you realise, ‘Oh, that’s already been done.’” This is the eternal dilemma for any designer selected for this prestigious annual commission: how to concoct a novel structure on a tight deadline that will enrapture park-goers, entertain corporate sponsors, and appeal to collectors, who are ultimately expected to acquire the thing – as well as, most importantly, provide a shelter for an overpriced coffee. Co