I want to make a round PCB to be the ''mother board'' for my round robot, but i can't quite see how to do it with eagle, i've tried using the circle tool, but all it gives me is a circular copper pour...
IIRC you just make a square board, then define the round edge in the dimension and/or silkscreen layers. Keep your layout inside the circle. Then put a note in the comments layer (or whatever gets used as a comment layer) describing the board being cut to that circle.
Whatever pcb shop you're using may have specific rules/wishes about how to actually end up with round stuff too.