Where can I buy screws for the dual shock 4

Hi I was taking apart my dual shock 4 to replace the shell (first time) and I lost the 4.0mm screws that you use to screw down the charger port (we're the lightbar is). I also lost the 6.0mm screw for um... I think the mother board, (the black cover thing that you have to unscrew to take out the rest of the dual shock 4) so I was wondering were I could buy these screws especially the 4.0mm ones