i3-box evolves II: single-plate inspired Z axis.

i3-box evolves II: single-plate inspired Z axis. For single plate and box builds, with smooth rods up to 12mm

The curves look very roughly approximated.
I suggest to add rounding or a tapper to all the places where 2 faces join at 90 degrees to make it stronger.
Also a tapper to the holes to make everything you insert self centering.
Is it really necessary to have holes that extend to the outside with support only from one side?
What are the dark green insets? Bushings?

The faces do not mainfest on printed model, at least not with resolution I am using (0.3mm layers). Its possible to increase the resolution of the rounding.
Green faces are faces generated by substraction.

I assume by “holes that extend to the outside with support only from one side” you mean holes for the rods - this design makes it way easier to insert the rods, and they are supported by that rounded wall opposite the opening

Also, check my iteration 3 album missing/deleted image from Google+ - there are photos of the new parts

These parts could be much stronger with the same amount of material and printing time.

I will probaly round the inside corner at the base a bit, but otherwise I do not see any obvious place for improvement

Just ask yourself one question:
Where will the part break.
Then you quickly see where material is required and where it can be taken away.

@Marcus_Wolschon : Looks like you were right, adding some fillet on base helped a lot, now is the part stronger than my testing board (see https://lh3.googleusercontent.com/-ubxdBv3NtmA/UQV8vZgyylI/AAAAAAAAGFg/8nOrgWQ5CyI/s763/IMG_20130127_201342.jpg )
as opposed to previous version https://lh6.googleusercontent.com/-n_sCXU7v94k/UQVq5zxVydI/AAAAAAAAGEI/ZJftK0flems/s763/IMG_20130127_185744.jpg