wvmarle:
The rest doesn't need much power, and can piggyback on the main supply.
Note that 24V is outside the range of the Arduino power input (20V max, 12V recommended max). You can get around that by adding a 5V buck converter to supply the Arduino with 5V from the 24V supply.
Are your NEMA 17 motors rated for 24V? Stepper motors should have a voltage rating as well as a current rating.