Most of my prototypes got sold as the finished product. Only one or two were ordered as custom circuits so I made them neatly on stripboard (Veroboard).
When tens of thousands of copies of my design were ordered then I took my stripboard circuit to a local pcb/assembly place who made their own pcb prototype for me to test, then made the thousands where each one was thoroughly tested with a tester I also built on stripboard. All passed except two that had assembly errors and of the thousands that were sold, none were returned. Money! The profit was dripping out of my mouth, eyes and ears.