really cool build.
it’s interesting that you chose the Samsung 30Q as your cell, any reason not to go with a 21700 or even a higher current 18650 like the Molicell P26A?
it’s generally recommended to use wire or copper braid instead of nickel strips to form series connections.
However, when using nickel strips as series connections I’ve heard it recommended to use 1 layer per cell in parallel, or use an appropriate current-carrying amount for the total current of the p-group (so in your case, 60A/5A = 12 layers)
spot welding through 2 layers of nickel is a tricky thing to get right. the more layers you add the harder it gets to make a good spot weld all the way through without blowing through the top layers of nickel.
I highly recommend you check out battery builds in this thread and re-think your series connections.
on another note, have you planned your balance leads? and the placement of your BMS if you intend to use one?