The pantograph shape has longer legs than the body size in order to increase launch velocity. The geometry and elastic band length are such as to produce a very nearly linear increase in foot force as the wide mouthed frog takes off and hence gives a smooth launch.

The lego prototype shows the principle, but only jumps 100mm.

The  challenge is the detail of the design to achieve over 50 times this performance, by minimizing weight, and maximizing the amount of energy stored and which is then usefully converted into height.

Its best jump cleared 5.35 m and earned the Bronze medal