Printable I3 base

Now ABS safe!

Since the success of a 3D printable Y carriage in my current design, I have been requested to modify it for an i3.

This carriage is based on design and style of my highly successful carriage. The first design survived 3 re-designs of my 3D printer and about 2 years of use. Sagging due to radiant heat was what eventually lead to it being made obsolete. As such, I improved on the design, and I am happy to announce that it is now safe to use for ABS printing.

***Features***
The original design has been modified to accept the i3 Y mount and raised to fit into an i3's space. It has holes in the frame for zip ties to hold down the LMU88 bearings and the necessary attachments to stop the bearings slipping.

The part has now been updated to be 10mm thick, instead of the 5mm as bases were failing over long use. You can now use 3 point stabilisation, and it also has a mount for cable chains.

***Requirements***
It will require 16x25mm M3 screws and nuts to attach t