I downloaded the "Attitude Table" from that site, since the zip file is small.
Sort of bizarre site/file organization. As you can see, the zip file contains the 2D symbol as DXF and DWG, and the 3D info as 3DS, DXF and DWG.
Open Lib Part should convert a dxf or dwg into a 3D object - and works with the 3D DXF file here, but fails with the 3D dwg - which is a problem with their file.
Whenever there is a 3DS, it is preferable to dxf or dwg as there is a 'smoothing' option. (The 3DS import is a "goodie" add-on, downloaded from the Goodie site via the Help menu.)
However...the 3DS file references a texture file which is not provided in the zip file, so the result isn't great.
In general, 3DS lets you import and retain all texture mapping on all surfaces: there should be a 3DS file as well as a folder of textures. This is one method for SketchUp Pro users, for example, to export information for import into ArchiCAD as library objects.
In general, dxf/dwg format results in objects that have visible lines for every surface triangle, making the result not particularly appealing in 3D or 2D. The 2D can be tediously cleaned up. As far as mapping different colors/materials to different surfaces of a dxf/dwg-converted objects - there is a technique (also tedious) that can be used which requires editing the 3D script and inserting MATERIAL commands. Not worth the effort unless the object is something that simply cannot be obtained any other way IMHO.
Karl
One of the forum moderators
AC 28 USA and earlier • macOS Sonoma 14.7.1, MacBook Pro M2 Max 12CPU/30GPU cores, 32GB