A terminal cover for the typical 30A 12V regulated power supply, which I designed for my first 3D printer.
Includes hole for IEC plug/switch assembly: http://www.amazon.com/dp/B00511QVVK/ref=pe_385040_30332200_pe_309540_26725410_item
And mounting hole for a female (so it can't be shorted by a stray metal object) XT60 connector. There is a large section to allow for easy insertion of the other plug, a tighter section to hold the connector, and a smaller section in the back to hopefully hold the connector in place from being pushed backwards.
Design printed, and works nicely.
IEC connector slot required some trimming, but it was done with a fast, low quality print, so that might have to do with it.
I haven't bothered with the XT60 connector.
So I got this printed, and it works. I have not gotten a chance to try the xt60 hole, because I have not received the connectors in the mail yet.
To assemble this, you need a PSU like this one: http://www.amazon.com/SUPERNIGHT-Universal-Regulated-Switching-Computer/dp/B009EIANT2
There are many options for that; as long as it's that general form factor, it should work. The dimensions seem pretty standard.
You also need one of these connectors:
And some 10A 5x20mm fuses.
First, make sure the connector fits in the mounting hole. Mine was a bit tight, but easily fixed with a knife.
For wiring, I used 14AWG wire. It's excessive for the AC wiring, which isn't going to be using more than 3 amps or so, but you can use the same wire for the 12V line to the printer. I'd recommend just dismantling an IEC cable for the wire; it has the proper coloring, and is more convenient than having to buy a roll of wire.
Solder a green wire to the ground connector of the socket. Keep it short-ish, because it will have to fit inside the cover to connect to the ground terminal on the PSU.
The other two connections on the socket go to the switch. The switch is a SPDT switch, so it can be wired to switch both the line and neutral wires. Use a multimeter to determine which connections are which. Double check, you don't want to mis-wire it! There should be two pairs of contacts; the contacts in each pair should be shorted to each other only when the switch is on. One contact in each pair has a small wire running from the bottom; this goes to the light inside the switch.
Solder a white wire from the neutral connection to one of the pairs of switch contacts; solder it to the contact that does not have the small wire for the light, so the light will switch on and off. Solder another white wire to the other contact in that pair.
Do the same for the live connection; black wire from the socket (the terminal is after the fuse) to the non-light contact on the other pair on the switch, and another black wire to the other contact.
The green wire goes to the PSU ground terminal, and the white and black to the neutral and line terminals, respectively.
Connect the wires that go to your printer to the + and - voltage supply terminals, and you should be good to go. Double-check to make sure that none of the socket connections are shorted to each other, and make sure the ground terminal is shorted to the casing of the PSU, and then plug it in to see if you get around 12V on the output.
Drill out the mounting screw holes a bit to fit whatever screws you're using, and mount it onto the PSU.
See the source things for more info.