I have not yet succeeded in making a quadruped, but 6 legs should provide sufficient balance. I will work on that in the near future: I'd like to include a gait-switcher using the gear shift from the Super Car.
From a simplified leg design, I have recently (1998) constructed a fully animated bipedal dinosaur.
But these efforts are pretty meagre compared to Kazuhiro Umeda's walking biped robot (movie included!).
990730