There is (or at least used to be) an "electroless nickel
plating" solution offered for plating vias through printed circuit
boards. (There was also an "electroless gold" for the same purpose.)


Most of the parts that I make that get plated are done in electroless
nickel, as that's what was original for Lotus.
I don't know who does the work, but can find out who our California source
is if you want it.
--
Stupendous Man,
Defender of Freedom, Advocate of Liberty