The device comprises a substantially planar body 12 having a resiliently deformable outer peripheral portion, a cell frame 114 and an inner array of detachable cells 22’. Each cell comprises coupling means which permit the cells to detachably couple with the cell frame. The outer peripheral portion may comprise a plurality of segments (82, fig 10) each comprising coupling means which permit the peripheral segments to detachably couple. Each of the cells may comprise a first cell portion 62A and a second cell portion 62B which may comprise a male of female connector. The cell coupling means may comprise a channel (69, fig 15) such that the cell frame is located in the channel when a cell is coupled to the frame.
