I HATE plumbing and will pay the man who will do it for me. I had to do it a lot when I worked for my Dad in high school and when I was broke and needed extra cash. Hated every minute of it.
Carpenters work a LOT cheaper than I do! I love working with wood, so if someone wants me to build them something, I'll do it, just at my regular rates.
I have also seen old buildings where the lighting circuits were pulled thru the old gas lighting pipes as a retrofit. One still had the gas supply connected (but turned off at a valve).
I had a house in Seattle built in 1910 that was down the street from a gasworks plant, so all the homes, which were originally built for the plant workers, were lit by gas My house was built without electrical wiring at all, so it was wired in the 20s or 30s and they did in fact use the old black iron gas piping for the light fixture wiring. Some of it was 3/8ths! That was fun to fix anything...