Tantillus carriage - 8/12mm bushings

Overview:
Tantillus carriage designed in OpenSCAD for 8/12mm bronze bushings.

Datils:
- two versions:
- - universal hoted mount - 4 x M4 bolts
- - j-head hoted mount 3 x M4 bolts
- low profile
- distance between rods - 17mm like default Tantillus
- Magneti Marelli bushing 140653

Notes:
In case of j-head hotend take the correct version left or right and print jhead adapter.

To be done:
- dual head version
- bowden mount

Derived from:
http://www.thingiverse.c