The standard plastic printrbot base allows the z-motor to rock - this one doesn't.
Optionally you can also use linear bearing clamps instead of zip-ties to hold the y-bearings in place.
My tested clamps have 4 holes for screws. I've added other two holes to this version. This is not because you need 6 but because you have the choice to use fewer - 2 may be enough but I haven't tested this.
The zip-tie slots are still there if you want them.
Also the motor has been moved 0.5mm to match the spacing between the traveling Z-nut and smooth rod.
And there is more.
There are holes you can tap for screws which lock the smooth rod.
There are also some mounting holes to screw the base down if you want too.
The Y motor works fine the way it is but I'll probably add support because I can.
Z+Y is working.
There is a problem with spanner access. I've enlarged the hole in the CAD file but I'm not sure how well it will work.
The test print is printed at .1mm and there is no real sign of ripple in it.