Rhombic dodecahedron

Dear all,
I am trying to design a rhombic dodecahedron from gallium arsenide (https://en.wiktionary.org/wiki/rhombic_dodecahedron). So far I helped myself by combining a cube and six pyramids, but this is not very convenient. Is there a straightforward way to script such a structure? I tried with the planar solid object but did not succeed. Can anybody help with a hint?
Thank you very much,

Hi, Sebastian!

I suggest you search for a stl-file of the element in the internet or construct the file yourself.
Then, you can import it to lumerical:

Notice the following information:

Please, keep me informed how it is going with your issue.