Which Porter Cable tools are made by Flex?
Probably no current ones. I believe Porter Cable used to own the Flex brand and its parent company, but after Black and Decker bought Porter Cable, the Flex brand was sold off to someone else. Now I believe it's owned by a Chinese company, but a lot of the more expensive Industrial and Professional tools are still made in Germany.
When Porter Cable bought Flex, they sold the tools as "porter Cable Flex" brand in the USA and Canada. I've seen a number of specialty tools made by Flex for sale on ebay at one point or another. I'm not sure whether the entire Flex line of tools was sold in North America, but the number of tool models was more extensive than what is currently sold in the USA.
There were also tools sold specifically under the Porter Cable brand rather than the Porter Cable Flex brand, that were made in Germany by Flex, but with differences. Angle grinders and polishers were made branded Porter Cable, and obviously based on the Flex models, but they usually lacked the specialty electronics, such as constant speed control and variable speed, used in the Flex models. The Flex made Porter Cable branded models were also about half the price of the Porter Cable Flex branded tools.
When Black and Decker sold the Flex brand, a lot of Porter Cable Flex tools got dumped on the market as closeouts. Unfortunately the supply has mostly dried up.