So started to design the very first replacement part und I'm somehow "optimistic", that more will follow.

Update 07.12.2015:
Uploaded the z-sliders to fix a lot of issues with the original design. Files are zslider_left6.stl and zslider_right6.stl. Both need to be printed with support structures. recommended settings are 25% infill and 0.2 mm resolution.

Update 08.12.2015:
Had to update zslider_left6.stl to zslider_left7.stl as there where some issues with the pocket for the x-endstop switch (diameter for screws to small, length to short).

Update 14.12.2015:
Added xcarrier_main13.stl and xcarrier_helock13.stl. Provides mount for single hotend, fan and proximity sensor (LJ12A3-4-Z/BY).

Update 16.12.2015:
Added corner brackets for the bed-frame. The files are bedframe_bracketA.stl and bedframe_bracketB.stl (mirrored). You need two of each.

Update 17.12.2015:
Added mount for z-axis stepper motor. The file is zstepper_mount.stl.

Update 18.12.2015 (a):
Added a part to mount the bed-frame to the x-axis rails at the bottom in a squared angle. The file is bedframe_crossmount.stl. You need two of them.

Update 18.12.2015 (b):
Added a second version of the right z-slider, because 3rd-party brass-nuts are slightly smaller then the original brass nut that comes from cobblebot.
Please note that you need either the one OR the other:
zslider_right6.stl ...is for the original brass-nut that comes from cobblebot
zslider_right_3rdparty.stl ...is for slightly smaller ones, purchased from 3rd party

Update 19.12.2015 (a):
Added a replacement part for mount of y-idler. The file is yidler17.stl.

Update 19.12.2015 (b):
Added a replacement part for joint mounting of the y-stepper motor and the y-endstop.
Note: for easier and cleaner wiring, the both electronic parts where put together and shall be mounted at the back side of the printer (idler to the front).
The file is ymount19.stl

Sidenote:
Some of the STLs have a quite challenging geometrie that requires support structures.
I decided to design them by myself and not to use the slicer function as slicer seems to create far to much unnecessary supports and give a hard time to clean them off.
Those additional STLs are available but nut yet published as it is unclear if there is someone interested in.
Please leave a short commend in case that you want to see them also published.

Update 20.12.2015:
Updated ymount19.stl to ymount20.stl and bedframe_crossmount.stl to bedframe_crossmount20.stl for minor fixes that showed up during installation.
For the ymount, the screw-holes where moved by 1mm for easier installation.
The bedframe-crossmount has been 'slimed down' as the corners collided with cobblebot "5 Point Connecturs" during installation.

Update 21.12.2015:
Added a replacement part to mount the thoothed belt to the bottom of the print bed.
The file is bedbeltclamp21.stl

Update 22.12.2015:
Added an spool holder that goes on top of the upper x-rails.
The file is spoolhldr22.stl

Update 22.12.2015:
Added bars in size 10x2x200 mm. They fit in empty slots of the aluminum extrusions and can be used to hide wiring inside those slots.
The file is slots.stl

Update 04.01.2015:
Made a different design for the spool holder as it turned out that the first version had to much rolling resistance and didn't worked well. The new design uses ball bearings for smooth rolling. The spool width can be adjusted as needed.
The ball bearings are 22 mm OD, 8 mm ID and 7 mm width. There are 4 of those ball bearings required. Further more you need 4 M8 x 30 mm screws and 4 M8 nuts. The files are spoolbb_slide_25.stl and spoolbb_rail_25.stl. Two of each are required.

Update 08.01.2016:
Changed the design to dual z-motor support to eliminate x-gantry sagging. This requires the 3D printed parts zmount_right30.stl and zmount_left30.stl and updated versions of the left and right zsliders, zslider_left30.stl and zslider_right30.stl.
Of course you need also a second set of lead screw, bras nut, stepper motor and motor/screw coupler. From the tests I can confirm that this mage a huge step forward into print quality and is worth the effort!

Update 06.02.2016:
Added a housing for controller and LCD display. Filename is controller30.stl.
Recommanded infill is 10% with support structures enabled.