Summary

The Printrbot Development Platform, for desktop-friendly Printrbot tinkering!

50mm fan mount to cool down foot and printrboard.
RaspberryPI B+ mount.
Arduino UNO + Breadboard mount.
Ultra LS 350W ATX housing.

All neatly forming a sturdy foundation that hides away all wiring and tinkering awesomeness that you would like to do.

Instructions

Has been successfully printed on Simple Metal Printrbot's in different ways:

Make One (draft made by myself):

0.4 mm layer height
1.75 mm ABS
260C hotend
90C heating bed

I printed the middle house with slot for fitting the ATX breakout board cable again with different settings, much faster with E3d vulcan hot end and Titan extruder. (See picture with red board attached to the side)

0.6mm layer height
0.8 mm hot end tip
1.75 mm PLA+
220C first layer, 205 rest
70C heating bed

Make Two and Three:

0.2 mm
1.75 mm PLA
200C hotend
No heating bed
Ref - http://www.thingiverse.com/make:120451
Ref - http://www.thingiverse.com/make:120693

You need to print out in all 6 modules:

2 foot modules (front and back). This is the modules that the Printrbot will stand on. The front one has holes for attaching a 50mm fan and two power-switches with 6mm hole diameter as well as 4 led lights (for example to show if power-switches are on/off).
2 housing modules for the ATX cabinet
2 modules that forms a bridge between the 2 foot modules and the ATX housing

Note that there is a version 2.x of one of the foot modules that supports attaching an ATX Breakout board with its acrylic housing. This is useful if you would like an all in one powerbench using bananaplugs as well. You will no longer need the jumper cable on the ATX if getting an ATX breakout board. See this post for more info: http://dangerousprototypes.com/2013/02/18/atx-breakout-board-v1-2/

Once all is printed (it takes 6-16 hours per module depending on the quality you choose you can assemble them. Start with the ATX housing, that's easiest.

The ATX goes standing up with the fan facing right, power cable and button facing back and all the other cables facing front. Put in plastic strips in the holes first, make sure the knot goes on the outside as it is very tight. Screw the bottom piece first, then the top. If the holes are misaligned, you can drill new ones (will fix this eventually)
Attach the bottommost strips with the bottom bridge module (the non-triangular one). Wait with the triangular one to last as it gets tricky otherwise.
Attach the back foot (the one with Arduino + Breadboard mounts in it). Make sure that you face the side where the rails ends in a wall backwards towards the bridge module. Strip it together with the bridge module.
Strip together the front foot (the one with fan facing front, RaspberryPi B+ mount and rails going through the whole top).
If you printed the back foot that has screw holes for the ATX breakout board, now is the time to fasten it to one of the sides (you choose!). You can attach the cable also to it.
Cables you don't need can be bundled together within the bridge modules (and covered with the triangular top piece)
Cables you need you can stretch through the two feet (in the middle). You can always strip them to the sides using the two circular holes in the middle foot.

Separate instructions will follow for powering the RaspberryPi B+, Arduino and other devices once I got it going. If you don't plan to do this you can always lead your power cables through the triangular back holes and on the sides of each foot.

At last, place the Printrbot on top of the rails gently. It should be very snug and sit tight. It is easiest if you lower it straight down as the rails are quite deep.

Have fun! :)