Added new Carriage that I redesigned and a new mount that fits it.
There are many different versions of the SmartrapCore. It has been revised by Smartfriendz many times since they first released it.
This design only works for the original carriage with 8 mm rods. But since it looks like new versions have different carriages, I've uploaded the STEP files for the mount and clamp if you want to edit the design. OR you can download the 8 mm rod carriage from here.
I originally found it at https://www.youmagine.com/designs/smartcore (under download, V1.2, click the gear and then edit in OpenJSCAD) which allows you to adjust parameters and set the rod sizes to 8 mm.
This is my design for an E3D extruder mount that fits the SmartrapCore. It's sturdier, simpler, and can be installed on the 8mm rod x-carriage.
It also provides enough room to use Tom114's E3D integrated layer fan design: http://www.thingiverse.com/thing:1746358 which uses a 50mm radial/blower fan along with the original Prusa i3 mk2 fan nozzle.
With the Smartfriendz extruder mount, I only used the bottom two mounting holes of the carriage with the top two slots of extruder mount. This was necessary to put the nozzle low enough as the E3D v6 isn't very long. But it wasn't a sturdy setup.
This design uses all four holes and incorporates seated nuts.