Martin Raynsford has built a cool looking laser cut walking robot. It was cut from 3mm plywood which is also a favorite of mine. In the video you can see how smooth the action is. Looks like the built might have taken quite a bit of time since there are a ton of small pieces and each one was connected using bolts and locking nuts. The motor sounds a bit underpowered but that is a simple fix. If you want to build your own or experiment with a similar design Martin has the design files available here.