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.

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