LAUSR

so does the list of bespoke materials. In the absence of a materials library, this can be confusing and problematic. 3-D printing is a collective term for at least nine different technologies, each with its own advantages and disadvantages. Materials may be limited to a particular method. High specification printers are able to produce composites, allowing users to modify the properties of different areas of the model. However, these machines require a significant initial investment. Although the absolute cost of materials may be low, converting data from a medical image to a 3-D printable file is not an automated process. Depending on the complexity of structure under study, the man-hour cost per patient for a proficient user will be at least 2 h for a simple model of the trachea and bronchi in our own experience. Training to use the software is an additional cost. Figure 2 illustrates our current progress, being a recent patientreconstructed model of a complex upper airway with significant glottic stenosis after chemotherapy and radiotherapy.