Abstract: A kit of parts for forming a structure which may be a play structure or a shelter, and which is at least partially of dome-like shape and which can resemble an igloo, comprises a series of side panels of generally trapezoidal shape each with side edges which are at least partially bowed outwardly and are capable of being joined edge-to-edge to adjacent side panels when curved to conform to said dome-like shape. The side panels are longitudinally flexible, and each has an upper end portion which is pleated to allow the upper edges of panels to be pushed together as the panels are joined. A convex top closure is provided for fitting over the top edges of the panels, and the pleated upper end portions allow ventilation around the edges of the closure.