I am looking for an alternative to the wire chain that is so expensive
I have an idea to use 1-1/2 aluminum square tubing 1/6" wall as a conduit the top one for dc and the bottom one for ac the router plug will fit through the 1-1/2 " square tubing. I have shown it fully extended but you can never let it go that far as it will lock in position, you can use 1/4" button head screws with lock nuts ( the head inside and the nuts outside, I have shown one plate but i think the square tubing needs to be sanwinched between two,
That's basically how Lionclaw did his arm on the Y-axis. He posted his plans on here and you can build that arm out of MDF or plywood. I would think putting a plastic washer between the "hinged" parts would reduce friction between the moving parts.
Attached is a screenshot of it.