Good luck with that.
Is there an alternative you could use?
ebay with distance filter
I am trying to think of the American company, Mc something where you can buy anything, bolts, copper, rod, nuts.
Its quite a popular store, with a good online catalogue, perhaps they have copper strips for you to tab weld.
LOL All I typed in was "threaded rod Mc" and I found it
I know thats not what you are looking for but I knew they sold it.
There is a chance they might have something that is copper. Doubtful on the nickel.
Edit - My casual 1 minute browsings found these.
1/32 smallest size - https://www.mcmaster.com/#solder/=1dkicly
Try a metal supply shop, find really thin copper.