Here is a 3D printed soft 4-legged robot that can walk on rough surfaces. Engineers at the University of California San Diego made it from soft and rigid materials. The robot can move over sand and pebbles and climb over obstacles. Its X shape layout allows it to adapt to various terrains.
Researchers successfully tested the tethered robot on large rocks, inclined surfaces and sand. The robot also was able to transition from walking to crawling into an increasingly confined space, much like a cat wiggling into a crawl space.
The legs are made up of three connected sealed inflatable chambers 3D printed from a rubber-like material. The chambers are hollow on the inside and can be inflated. The above video shows the robot in action. More info is available here.
[Source]