Today I almost finished my lamp.
First of all, I found a lamp and I looked for a way to fix it on the pipes. I wanted to keep the original articulation to stay as flexible as possible. So I cut the plastic the same diameter as a copper pipe I got and I fixed it into the connection with hot glue.
The only problem is the articulation which is in plastic, not aesthetic at all but I plan to do a metal imitation painting to fix this issue.
I also did the electrical connection and the lamp is working for now.
Last steps are now the painting and finding another support to ensure a better stability.