Here's one with balloons filled with coffee/sand for irregular surfaces: https://www.popsci.com/technology/article/2010-10/coffee-filled-balloon-makes-best-robo

Here's one with balloons filled with coffee/sand for irregular surfaces: https://www.popsci.com/technology/article/2010-10/coffee-filled-balloon-makes-best-robotic-gripper https://www.popsci.com/technology/article/2010-10/coffee-fil...