The idea of welding small sections ot tubing isn't that bad. If you do it symetrically it could look like part of the design.
I'm confused about the UL standards. i've been making lamps out of stuff since I was a kid, and no one had ever asked me about this. Is there someone who has to approve the work?
For example, I once made a fish tank light using a small candleabra socket and a conch shell. The switch was a simple "in the wire" add on, and the whole thing set nicely above the cover of the tank. Would this need to be approved, and how would you get this approval?