Great video here of the process he used to make a PCB in the early 80’s before it went to production - it’s a parallel printer buffer device to go in-between a BBC Micro and the printer.
-Gordon
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Brings back memories of letraset, transfers and transparency acetate. Spraying copper board with Positiv20 spray and then exposing … I am now quite happy I dont have to do that anymore. I ruined many shirts with ferric chloride 
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