Power strip that handles a maximum total draw of 10A at 120V AC. You can change to a IEC 320 C7/C8 if you want to higher current. I used PrusaSlicer for the prints. (Need minimal supports) 

The tolerance is tight so it needs to be fit together with a mallot, that will create an interference fit and will hold the modules in place. 

To finish making this, you will need: 

• M3 nuts and bolts. (6-10 mm in length) : 3 per module and 2 for fastening the IEC socket.
• IEC C5/C6 connector/ cord (I bought mine from AliExpress) (You can salvage a cord from some laptop chargers)
• Rocker switch rated to 10A. (20 mm mounting hole) 
• 18AWG wire or thicker. (preferably 16 AWG but 18 AWG works in a pinch) 

Once you assemble however many modules you want together, you just run the wire through the holes and solder or mechanically crimp the wires to the sockets' leads. (Earth goes to the top, live or black wire goes to the smaller slit and the white or neutral wire goes to the longer slit.) Wire all sockets in parallel. Connect the live from IEC connector to one end of switch and the other end to the live of the sockets. Directly connect the neutral and the earth from the IEC connector to the neutral and earth of the sockets. And that's pretty much it.