Often I have to use standard metal (steel, aluminium...) profiles in projects, modelling these profiles is, of course, simple, sketch the section and then extrude it, but it might become a repetitive work.
My suggestion would be to have a library with standard profiles (pipes, rods, tube, 'I' beams, etc...) and with the ability to add new profiles, with the specification of material and information to populate the BOM. With this in place one would need only to select the plane, point of placement for the profile, direction and height of extrusion or path for extrusion. The user could also set any material as the profile material (metal, plastic, rubber, wood, etc).