This circuit board enables you to switch the three power rails to a connected SATA device. All three voltages (3,3V , 5V and 12V) can be turned on and off independently.
Three status LEDs indicate whether input power is applied, and 3 other LEDs indicate whether the power is being supplied to the external device.
4 User-controllable status LEDs are also present.

We encased our PCBs in old tape-cases, and connected the circuit board between a cut-in-half SATA power extension cable.
Both the case and SATA power extension cable are NOT included.

Datasheets:
AT90USB162
FDS8884 (5 & 3.3V)
IRF9333 (12V)
Documentation for the complete PCB