That one has the middle section at an angle routed for a FD, a U brake one has a straight middle route.@brokenbloodybritain this?
https://www.sjscycles.co.uk/gear-spares/bottom-bracket-cable-guide/
Only suggest 3D print as assumed you had looked everywhere. SJS was the first place that sprung to my mind with parts like this. Not sure if it’s exactly what you need?