2 Power Supplies Necessary?

The parts list calls for a power supply available from Amazon - power brick style. It has a plug that looks like it fits the Arduino Mega.

I would think that the RAMPS board would need a separate power supply to drive the motors, but I don’t see that listed as a part. Or does the one power supply feed both the Arduino and RAMPS boards?

Nope 5A is enough for everything and an extruder. You only need more power for a heated bed.

So the Arduino passes power through to the RAMPS board? That’s cool.

The other way, ramps passes some through to the arduino. The ramps is capable of using 2 power supplies as well, so it is an easy upgrade with no wasted money.