I am new to this forum. I want to create a mechanical structure as depicted in the image A pangolin bag. And further wouls like to automate the closing and opening of the bag. But I am facing issues with the design and movements of these layers. One layer is blocking another layer from moving or i must say rotating. They kind of block each other . Is there a sophisticated design to achieve this ?? Simply cutting flaps(layers) of equal length won't work. I think the lowest flap should be of smallest length. But the problem arises when you punch hole these layers by a same amount of length and then try to rotate them. They blocks

  • $\begingroup$ Welcome to Robotics Hrithik Baishakhiya, but I'm afraid that Unbounded Design Questions are off-topic because there are many ways to solve any given design problem. We prefer practical, answerable questions based on actual problems that you face, so questions which ask for a list of approaches or a subjective recommendation on a method (for how to build something, how to accomplish something, what something is capable of, etc.) are off-topic. Please take a look at How to Ask & tour for more information on how stack exchange works. $\endgroup$
    – Ben
    Apr 13, 2019 at 0:19
  • $\begingroup$ have another look at the backpack on amazon.com .... it is quite clear how it operates $\endgroup$
    – jsotola
    Apr 13, 2019 at 0:46

1 Answer 1


I would work backwards, looking at the design when it is closed. From that, you'll see how much larger each piece needs to be than the one below. Each piece is probably connected to the one below it with fabric.

To actuate this, you could simply rotate the top-most piece upwards, which will pull the pieces below with the fabric connectors.


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