Figure 4 .

Examples of two homemade gene guns. A, B) A plastic gene gun made from a slightly modified 5-dollar water gun. A) The only modification required was to connect a Millipore swinex filter tip to the nozzle for compressed air. This was achieved by removing three screws in the plastic body, followed by the plastic nozzle cover (arrow). B) The $5 gene gun with the filter tip screwed into the cut-off nozzle (arrow). C) An example of a metal gene gun built for approximately $50 from parts at a local hardware store (see Materials and Methods for construction details).