A 40 mm fan guard with the Brotherhood of Steel emblem.
Made with Inkscape and Blender. The
.blend file can be directly exported to STL; just make sure to adjust the units as appropriate. You can also render it to produce the thumbnail image.
A 2D design was made with Inkscape using an SVG from Nukapedia as a base. Air holes were cut into the wings, and the basic frame was made mostly from primitive shapes using boolean path operations.
The resulting SVG was then imported in Blender, and the paths were converted to meshes. The frame and emblem meshes were joined manually with degenerate vertices and edges mostly automatically collapsed. "Limited dissolve" is your friend for these operations.