I visited a pcb making factory once. Left with an appreciation for the amount of work needed for 80-layer pcbs, and knowing I would not want to deal with making them myself.
my goal was simple 2 sided pcbs, machined traces because i wanted to avoid chemical etching, but when it comes to via's chemicals are really the only way. The chemcials needed for plating via's are very toxic. my current thinking to avoid the really nasty ones is to try conductive ink (probably pretty bad too) but it maybe would work to coat the fr4 material and then allow a copper plating to take... really it's a fun process machining and laser the soldier mask.
