3D Model: Rotating Square Auxetic Structure

Subject: Corrected Specification: 3D Model of Rotating Square Auxetic Structure with Open and Closed Cells

Dear Specialist,
I need a rotating square auxetic structure, not a honeycomb. This is based on the scientific concept shown in this Nature article: Figure 2 from Nature .
What is a rotating square structure?
· It consists of an array of square islands connected at their corners by thin ligaments.
· When the structure is compressed, the squares rotate relative to each other .
· The spaces between four adjacent squares act as cells that can open or close.

My specific requirements:

1. Overall block dimensions :
· Length: 290 mm
· Width: 120 mm
· Height (Z-axis): 10 mm (critical)
2. Square element geometry:
· Square side length: 6.5 mm (range 6-7 mm acceptable)
· Square thickness (in XY plane): must have a gradient:
· At the corners (where ligaments connect): 1.2 mm
· At the center of each square edge: 1.8 mm
· Smooth transition between these values
· Square height (Z direction): 10 mm (same as block height)
3. Ligaments (connections between squares):
· Located at square corners
· Thickness: 0.6 mm
· Length: should allow squares to be spaced with initial gap of ~0.5-1.0 mm
4. Cell types (this is the hybrid part):
The spaces between four adjacent squares form "cells". I need a checkerboard pattern of open and closed cells:
· Open cells: These spaces should be completely open from top to bottom (no top/bottom membrane). They will later be filled with elastomer.
· Closed cells: These spaces must be sealed at the top and bottom by thin membranes (thickness 0.3 mm), forming an enclosed cavity. The interior should be empty.
5. Pattern arrangement:
Imagine labeling the inter-square spaces in a grid:
· Row 1: Open, Closed, Open, Closed...
· Row 2: Closed, Open, Closed, Open...
· And so on.
6. Important notes:
· The entire structure must be a single solid model (manifold) suitable for 3D printing in TPU (flexible filament).
· All vertical walls should have the specified gradient thickness.
· The bottom of open cells is open (no membrane).
· The outer perimeter of the block should have solid walls (~1.5 mm thick) to hold everything together.

Visual reference:
See Figure 2 in this article for the basic geometry: Nature article figure . My structure is similar, but with varying square thickness and the hybrid open/closed cells.

Deliverable: STL file ready for 3D printing.

Please let me know if this is clearer. I can provide additional sketches if needed.

Best regards,
Vlad