A method of forming a support structure on a base from a framework uses a tube of a flexible material divided by dividing walls of flexible material into an array of compartments. Each compartment includes at least one wall including a hollow protrusion or recess. In use the framework is located on the base and the compartments are filled with the filler material so that each compartment is adjacent to one or more other compartments filled with the filler material and so that each hollow protrusion fills with the filler material so that each compartment protrudes into or is protruded into by at least one adjacent compartment so as to interlock adjacent compartment. This increases the overall strength of the support structure.