1.16 Classifying shapes
1.6.1 (2D) continuous
If the profile of an artefact does not change along its length – like a pipe, electrical cable or aluminium cooking foil – then it can be classified as having a simple (continuous) 2D (shorthand for two dimensional) shape. Many 2D products are used as the raw material for processes which make them into three-dimensional shapes. PVC window frames for example (Figure 13) are made from continuous extrudate (the product of the process of polymer extrusion) which is cut into suitable lengths and then joined together by fusion welding.