Pipes and bars are extremely common in Doom 3 techbase levels, especially safety railings. But working with patches to make increasingly elaborate rails is really time consuming and doesn't need to be. I see that DarkRadiant lets you draw volumeless curves (which are probably used for cutscene cameras), and they look like the perfect candidate to "extrude" into pipe (curved cylinder) patches. I haven't found any native menu option that can do it, and nothing on Google either, so I'm asking: has anyone made a Python script that can do this already?
most likely the best place to ask that question is the Dark Mod forums, since they'll know more then most people here will: https://forums.thedarkmod.com/
if they do have that feature that would be pretty cool. You could always use Blender & make your pipes in low/ase format & import them.