Unfortunately, it seems that all the free 3D models for electronic components are available only in STEP or other Autocad something file formats. I searched the web and it said use FreeCad. FreeCad does not seem like a stable, user-friendly application. It crashed when I opened certain STEP files or sometimes failed to export certain STEP files to certain formats without telling me the details.
Anyway, even if I succeed to export it, the colours are lost. For example, I downloaded this file ( https://grabcad.com/library/lm2596-dc-dc-buck-converter-module-2 ). As you can see, it has colours when opened in FreeCad.
But if I export it as STL/DAE, it looks like this in Blender.
When exported as OBJ, Blender did not display anything, and exporting to glTF failed.
Is there a way to import a STEP model with colours?