I was going over some of my bikes today and noticed all of the Bottom Bracket cable guides were a little different. Even within the same brand there were differences. It got me thinking about how little I know about this frame component. So help me out with info on cable guides. Were they made by the frame/dropout/lug companies or the builders themselves? Was this a detail of the bike that the builder would try to make stand out? Any info would be interesting to discuss.

Different builders different styles, Also Bottom Bracket manufacturers had their own designs.

I prefer the ones that are built onto the BB shell, but from what I understand, the bolt-on plastic ones are less trouble. My D'Arienzo has tubes the curve under the BB, with a clear plastic liner inside and caps on each end. That's a nice touch, and very easy to keep lubed and clear of debris.

When we are in the Portland/Vancouver area (month or two at a time) I really don't like getting the grime slurry carried into BB tubes on my customs or even the Pinarello pathways inside the BB. I have been pondering how to do this with the sealed housing/cables being made today.
I have seen a few older Bassos and search D'Arienzo but could not find such a BB.
Would love to see any photos or details on the liner caps if not too much trouble.
Thanks

The ones I have that are protected best from the weather have cable stops on the lower downtube, one the driveside chainstay and housing that goes between. No gunk gets in and no paint gets worn off from cable rubbing.