[SAump]

Fielder's cap? If it were whiskers away from foul, I would expect the fielder to pick it up barehanded and attempt to make a play. I would allow the play to continue live and pick up the players reactions before I make that 3-B award decision. I doubt I would award all 3 if B/Rs reached bases safely or attempt extra bases at their own risk {Similar to balk ruling}.

Catcher's helmet? I would rule that the ball had no chance of going fair, foul ball because the catcher was all over it. But if it were whiskers away from foul, I would also expect the catcher to pick it up barehanded and attempt to make a play. Need more info. I would also have to see B/Rs reactions to make that decision. If either gives up, most likely the batter-runner, I would not make the 3 base award, I would have a foul ball.