How do I deal with the high amps in this Arduino circuit?
Each of these devices will have various ratings, and it's important when looking at the whole design that none of the ratings are violated, or you risk something burning up.

Lets start with the motors:



Ok so 400mA each at 12V.

These are connected to the Dual L9110S  H bridge Motor Driver. The rating on that is 12V 800mA per channel


So far so good.

There are 6 motors, and they are all being powered by the 12v power supply.

The power supply will need to supply at least 400mA*6 = 2.4A. The motors will require surge when they turn on, so give yourself some headroom here.

Note that the arduino is only sending low current control signals to the motor drivers. It's not supplying power for the motors. It's like you pushing the gas peddle on a car.

The arduino therefore doesn't have any current requirements. It simply has to send control signals of the correct voltage. The signals from the arduino will be 5V, and according to the datasheet of the L9110s, 5V will work fine.