The Palantírs

[Bruce MacCulloch]

I also recall a mention somewhere that the master stone resided beyond the sea in Eressëa.

Read the quotes in the post just above yours - it says it right there.

Feanor made them. That much I know, but what exactly was he looking for with the palantiri? What was their original purpose?

From what can be seen of Fëanor's character, I would say that it is highly probable he made them just "because he could".