These are a few different model generators built in Houdini. They take in a base shape (or a mix) and convert them to the detailed models.
The poly/tri pieced generator uses some fairly simple re-meshing and individual face extrusions, while the layered shapes are built by converting the base shape into a volume and extracting chunks from that.
You can find the models on Gumroad here: https://dctech.gumroad.com
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Or on ArtStation: https://www.artstation.com/undertow/store