 Packing can speed the bonding process and strengthen the structure.Small sticks, approximately 30 to 35 cm (12–14 inches) are pushed into the structure to act as thickness guides when the interior is hollowed out.According to Halfpenny and Ozane, the wall at the base should be at least 30 cm (12 inches) wide and at the top about 20 cm (8 inches) thick, though wall-base thicknesses of >60 cm (2 ft) are possible.