5. This all seems a bit complicated – and to some extent it is! But the idea is that two of these aluminium rods will be used for fixing the lizard’s legs to the shafts coming out of the gearbox, and the other one will be used for fixing the elastic band to the drive shaft of the gear box. The third aluminium rod has two M4 grub screws in it and a 6 mm hole through its diameter – about 4 mm from the end. This fixes onto the drive shaft with an M6 bolt through the 6 mm hole, such that there is a 4 mm gap between its head and the aluminium rod, and a 4 mm gap the other side (between the nut on the other end and the aluminium rod). The M6 bolt is for attaching the rubber bands that will drive the legs.

6. At the other end of the lizard’s body drill a 6.5 mm hole in the top of the tail, and screw a 70 mm length M8 studding into it to give a firm anchor for attaching the other end of the rubber bands to. On the underside of the tail make a keel out of the 150 mm length of aluminium angle. Cut one leg of it down to the bare minimum needed to fix it to the underside of the tail about 12 mm wide. Then screw it on with some short No. 8 wood screws.

7. To make the legs cut two 150 mm lengths of 3 mm diameter steel rods. Make a hoop at the end of each (by wrapping around a piece of bar) to give a hoop that can be glued strongly to the plastic feet. At the other end, grind or file a 2 mm wide flat on the side of the rod so that it can be held more securely by the M6 grub screw.

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