Confused about stepper sizing

[Desertboy]

"Selecting Supply Voltage

The power MOSFETS inside the AM882 can actually operate within +20 ~ +80VDC, including
power input fluctuation and back EMF voltage generated by motor coils during motor shaft
deceleration. Higher supply voltage can increase motor torque at higher speeds, thus helpful for
avoiding losing steps. However, higher voltage may cause bigger motor vibration at lower speed, and
it may also cause over-voltage protection or even drive damage. Therefore, it is suggested to choose
only sufficiently high supply voltage for intended applications, and it is suggested to use power
supplies with theoretical output voltage of +20 ~ +72VDC, leaving room for power fluctuation and
back-EMF."

from the AM882 manual obviously check your stepper driver specs first.

Personally I went with 68v on advice from the forums the PSU build was very easy with Clive S help and I spent longer worrying about it than it took to build which was about 2 hours with 1 hour of pottering, smoking cig and drinking tea.

Good luck with your build ;)