borrowed belt drawing shibby from mendel90 repo
put all parts into this utility scad mostly because i was sick of MCAD's quirks
renders GT2 pullies - taken from the mendel90 repo
added info about linear rod requirements and stuff about print quality and calculations of forces on axes
added measurements for smallest spline of all
corrected belt colour, added helper methods to render a GT2 belt
commented out vitamin module
major changes to the carriage - added centre cutout and refactored the
code a little
multiple changes: y axis fully rendered with belts, pulleys and
bearings. utility module for rods moved into another file. z carriage
has changes to reflect change in design, and to show the correct parts
major design change. using smallest spline available. corrected motor
end to have holes et al on the correct side. removed the need for having
multiple pullies attached. simpler design but its not finished yet