I was thinking about looking for a rubber grommet to put on the holes in the cross bar then sliding the copper enclosures into them... But 1. Finding exact grommets to fit would/will be hard (haven't given up on that idea yet) and 2. Just getting the enclosures to fit into the holes, from the inside, is hard enough. Again, another one of those things that would have been MUCH easier had I planned a little more. This project is more of an experiment / R&D type. I just wanted to know if it could be done cheaper than buying a pre-made and at the same time I wanted custom lights IN the cross bar because I have never seen it done before. I really like the idea of them there but the effort it is taking to get them there is growing more and more. Would help if I had the right tools... No suprise there at all... Said that a bunch of times in life already.

As far as galvanic corrosion... Never thought about it before you mentioned it. I had to google that to refresh my memory of what that even was. (I own a swamp cooler lol) I don't really know what I'm going to so about that. I currently live in the desert, so corrosion doesn't usually matter out here. But, I am moving in less than 3 months. Don't know where to yet, but I bet it rains more.

I have 5 kits of arctic alumina thermal epoxy. I was going to use that to attach the LEDs to the inside of the copper enclosures. I suppose I could use that to attach the enclosures to the aluminum cross bar but that is rather expensive.

This whole project is getting more and more Xpensive. I guess that's part of R/D though. Lol i'll bite the bullet on this one.