Brixelate and Kitify are two Blender addons written in Python that help designers create physical, editable versions of their designs. Check out the video below to see them in action.
Brixelate
Brixelate takes an 3D object and packs it full of LEGO bricks. The type of LEGO bricks used can be changed, as well as bounding the LEGO to within the object.
The next steps are to selectively Brixelate different regions of the object, leaving the rest untouched.
Kitify
Kitify allows the user to create LEGO compatible slices of their designs. Manipulating the cut plane gives fine control over the location and direction of the cut.
This means that design features could be swapped out or even built up with LEGO bricks.