Hello, As I mentioned in previous response please look into this post: Creating an Inverted Pyramid structure (ansys.com) you can make hollow geometry. Its explained step by step there. I am also copying the response here.
“Hi, you can either rotate the existing group 180 degree around y axis and shift it to the proper position. this example uses old technique of layered rectangles; or you can build up your own periodic inverted Pyramid by your own using the pyramid in object library:
what you need is to flip the sizes of the tip and the bottom:
it can be a solid pyramid, or can be air by use of 'etch' material mesh order.”
If you like to have one pyramid on top of another repeat the same step again by adding another array of pyramid.
For understanding mesh order : Understanding mesh order for overlapping objects – Ansys Optics
Please try it.
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