How do I repair pinholes in stainless steel cookware?

fill it.

Place a stainless steel pin in each hole and then grind both sides smooth.

Short answer: Even TRYING will cost more than a new pan AND finish destroying the pan.

how did it get pin holes did it happen on re-entry to earth what do you cook over there acid ?

buy new ones and avoid the Klingons

Duct tape

If it has holes, that is an indication it is not worth repairing. But if you are desperate and need a quick fix, put in a screw with a tiny O ring under its head. Heat will soon ruin the rubber O ring. Then if that is going to be a problem, use JB Weld epoxy in with the screw hole and screw. You gonna use it to water the dog?

You don't, at least not at home. You'd have to get someone to do stainless welding and chances are excellent that it would cost as much as a new pan.

My mother has a stainless frying pan that's 68 years old and still in working condition. I can't imagine how a stainless pan gets pinholes but it suggests that the pan is in really bad condition and more holes might appear soon even if you get the current ones fixed.