A method of forming a support structure on a base from a framework (10) comprising a tube (12) of a flexible material divided by dividing walls (14) of a flexible material into an array of compartment (16), is disclosed. The method includes the steps of locating flexible strings (20, 22, 24, 26, 28, 30, 32, 34) through lines of compartments (16) at or near each edge of the framework (10) and through lines of compartments (16) intermediate the edge lines of compartments (16), attaching the ends of the strings (20 to 34) to fixed objects (36) to support the framework (10) with a first end of the tube (12) on the base and a second end of the tube (12) above the first end, and filling some or all of the compartments (16) with a suitable filler material. The strings or stays assist in supporting the framework (10) when it is being filled with the filler material.